Article

Imaging the Invisible Using modified Digital Still Cameras for Straightforward and Low-Cost Archaeological Near-InfraRed Photography

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Abstract

Analogue near-infrared (NIR) photography has already been used a lot in both scientific and medical photography, in which cases near-infrared (NIR) radiation was mostly captured by InfraRed (IR) sensitive plates or film emulsions. However, its use in archaeology has remained rather restricted, most likely due to some ignorance and/or lack of knowledge about this kind of photography, while the critical imaging process also severely limited its use. This situation could be, however, changed completely, as the image sensors used in digital still cameras (DSCs) are very sensitive to NIR wavelengths, making the quite lengthy and error-prone film-based NIR imaging process obsolete. Moreover, modifying off-the-shelf DSCs even simplifies this digital acquisition of NIR photographs to a very large extent.By starting with a general outline of the ElectroMagnetic (EM) spectrum and the specificities of NIR radiation, the base is laid out to tackle the possibilities and practicalities of archaeological NIR imaging, subsequently comparing the earlier film-based approach with the digital way of NIR shooting, showing how the latter can greatly benefit from modified compact, hybrid and small-format Single Lens Reflex (SLR) DSCs. Besides in-depth information on the technique of digital NIR photography, examples will illustrate its archaeological potential.

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... However, they operate on higher infrared frequency color spectrum wavelengths between (380-750-nm). [74] The EM waves humans perceive -the so-called visible light -encompasses a very small portion of all EM radiation: only wavelengths between approximately 380 nm and 750 nm. [74] This takes into account the absolute thresholds varying from person to person and specific viewing conditions. ...
... [74] The EM waves humans perceive -the so-called visible light -encompasses a very small portion of all EM radiation: only wavelengths between approximately 380 nm and 750 nm. [74] This takes into account the absolute thresholds varying from person to person and specific viewing conditions. However, on both sides of this extremely small visible spectrum resides EM radiation the HVS is insensitive for, characterized by wavelengths smaller than 380 nm or larger than 750 nm. ...
... Just as visible light, these wavebands were divided into spectral regions and given names as gamma rays, X-rays and Ultraviolet (UV) rays on the short-wavelength side, while IR rays, microwaves and radio waves can be found in the long-wavelength region (Fig. 1). [74] However Fig. 1 is also following the original suggestions of the Electromagnetic spectrum guides, tables and diagrams followed from (adapted (Freedman and Kaufman, 2005, Figs. 5-7). ...
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Where exactly is the "true" Mount Sinai? Is it at the romanticized popularized location made by the controversial amateur archaeologist the late Ron Wyatt. Who first proposed "Mount Sinai was in Saudi Arabia". Ronald Stewart Author of this volume #1, shall present and demonstrate Scriptural, known and unknown new scientific, (AM)-(Angstrom-Microscope)-scientific application, microscopic, geological, Vuicanology, mineral, chemical, elemental, geographical, topographical, lost historical, archaeological, biblical archaeological including: "Pre-Hebrew-Writing-Petroglyph-Depictions", photographic, cross-comparison-photographic, and other various forms of evidence, provide an abundant wealth of new in-depth comprehensive diagnosis and analysis data and evidence. Not only questioning, the beliefs, statements, and claims, made by the proponents, that the Jabal-el-Lawz and especially that the Jabal-el-Maqla mountain sites are the true biblical Mount Sinai in NW-northwestern Saudi Arabia. But rather, that the true biblical Mount Sinai but is not in NW-northwestern Saudi Arabia, but that the aforementioned abundant wealth of new data and evidence will support, uphold, and defend, that the true biblical Mount Sinai and the culmination of the events of the Israelite Exodus took place rather at Jebel Musa. Which is today's accepted traditional location for the true biblical Mount Sinai instead.
... The fluorescence emission spectrum can be unique to each variety of chert, so some emit in the blue, the green, others in the yellow, and still others in the orange or red, and many do not fluoresce at all. Human vision perceives light only within a narrow window of the electromagnetic spectrum from approximately 400 nm to 700 nm (Verhoeven, 2008), a region known as the visible spectrum. However, fluorescence is not confined to the visible region of the electromagnetic spectrum. ...
... With the development of digital imaging using metal oxide sensors, near-infrared imaging was made available for archeology researchers (Verhoeven, 2008). NIRFI using a modified consumer camera (Verhoeven, 2008) is the application of visible excitation, even ambient solar excitation (Oh et al., 2020), with subsequent detection and imaging of near-infrared emission using a modified digital camera with a metal oxide sensor. ...
... With the development of digital imaging using metal oxide sensors, near-infrared imaging was made available for archeology researchers (Verhoeven, 2008). NIRFI using a modified consumer camera (Verhoeven, 2008) is the application of visible excitation, even ambient solar excitation (Oh et al., 2020), with subsequent detection and imaging of near-infrared emission using a modified digital camera with a metal oxide sensor. NIRFI is being widely used in clinical medicine to provide real-time internal imaging without surgical intervention, and there are thousands of medical reports using and developing NIRFI in that field (Altinolu and Adair, 2010;Jiang et al., 2009;Owens et al., 2016). ...
Article
Tiger chert was used extensively by Native American people of the Clovis lithic industry as the source material for stone tools. Although tiger chert occurs naturally only within the Bridger Formation of Southwest Wyoming, tiger chert artifacts have been found throughout the American west. This paper explores the previously unreported near-infrared fluorescence emitted from tiger chert upon visible excitation. The two objectives of this study were to demonstrate the utility of near-infrared fluorescence imaging (NIRFI) to tiger chert artifacts and to identify the chemical origin of the observed fluorescence. Tiger chert was analyzed by visible and NIRFI, SEM-EDX, ICP-OES, and fluorescence spectroscopy. NIRFI can be easily used to discriminate between tiger chert artifacts and the environment, since most materials such as soil and most rocks appear black in the resultant image. This suggests NIRFI should be utilized by archeologists at any site where tiger chert has been previously identified. Additionally, NIRFI was used to differentiate between tiger chert artifacts and an artificially weathered, recently-knapped tiger chert point, suggesting that NIRFI could be used to distinguish genuine tiger chert artifacts from counterfeits. Tiger chert fluorescence was confined to the manganese-and-iron-rich surface, suggesting the presence of desert varnish; however, red agate from the same site did not exhibit fluorescence, instead implicating tiger-chert-specific weathering. Thus, the chemical origin of fluorescence was not conclusively identified.
... Within an archaeological context, aerial photography from manned aircraft is an established technique used to record sites of disturbance and/or capture visual anomalies [26][27][28]. Common successful approaches include the use of invisible near infrared (NIR) photography to capture anomalies caused by potential buried material [29][30][31]. Although airborne hyperspectral imaging may be useful from a spectral point of view, the data still lack the necessary spatial resolution (4.7-5.2 m) to detect single targets [19]. ...
... Aerial photographs have long been used to detect visual anomalies in an investigative and archaeological context [3,6,[29][30][31] and the increasing incorporation of UAVs within policing, alongside the method outlined in this paper can further aid these investigations. The recent investment of UAV technology by UK and international law enforcement enables even the smallest law enforcement agencies to have constant aerial support [33]. ...
... With regards to clandestine burial detection all previous academic work has relied upon the use of custom or modified payloads, such as the addition of filters [35] or the modification of commercial cameras [29] to achieve positive results. As such, law enforcement is limited with implementing these approaches as these agencies lack the expertise or funding required to purchase or modify highly specific UAV devices. ...
Article
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Until recently, clandestine burial investigations relied upon witness statements to determine target search areas of soil and vegetation disturbance. Due to this, remote sensing technologies are increasingly used to detect fresh clandestine graves. However, despite the increased capabilities of remote sensing, clandestine burial searches remain resourcefully intensive as the police have little access to the technology when it is required. In contrast to this, Unmanned Aerial Vehicle (UAV) technology is increasingly popular amongst law enforcement worldwide. As such, this paper explores the use of digital imagery collected from a low cost UAV for the aided detection of disturbed soil sites indicative of fresh clandestine graves. This is done by assessing the unaltered UAV video output using image processing tools to detect sites of disturbance, therefore highlighting previously unrecognised capabilities of police UAVs. This preliminary investigation provides a low cost rapid approach to detecting fresh clandestine graves, further supporting the use of UAV technology by UK police.
... • False color (IRfc/UVfc...); are composite images digitally computed by swapping RGB layers in between IR/UV and VIS to link non-visible areas of interest with a visible falsecolor relevancy but could be also used for pigment mapping. An overview of the literature in this field permits to find all required technical set-up specifications for IR (Bridgman and Lou-Gibson, 1963, Verhoeven, 2008, Cosentino, 2016, UV (Cosentino, 2015) and false-color (Aldrovandi et al., 1993, Aldrovandi et al., 2005 practices. Commonly, CH examination surveys are often done by simultaneous applications of TP techniques and at different time range (see Fig.1) according to object's specificity and context, sometimes including experimental or hybrid techniques (e.g RAK/IR (Cosentino et al., 2014). ...
... Most of the time their application is required on different areas of a painted surface necessitating multiples handled acquisition which are hardly reproducible. However a registration issue remains concerning the combined multispectral aspect of TP documentation due to incoherent spatial overlapping (Cosentino, 2016) also known as short focusing and technically explained by longitudinal chromatic aberration phenomenon (Verhoeven, 2008, Hackforth, 1960. ...
Article
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In the field of wall paintings studies different imaging techniques are commonly used for the documentation and the decision making in term of conservation and restoration. There is nowadays some challenging issues to merge scientific imaging techniques in a multimodal context (i.e. multi-sensors, multi-dimensions, multi-spectral and multi-temporal approaches). For decades those CH objects has been widely documented with Technical Photography (TP) which gives precious information to understand or retrieve the painting layouts and history. More recently there is an increasing demand of the use of digital photogrammetry in order to provide, as one of the possible output, an orthophotomosaic which brings a possibility for metrical quantification of conservators/restorators observations and actions planning. This paper presents some ongoing experimentations of the LabCom MAP-CICRP relying on the assumption that those techniques can be merged through a common pipeline to share their own benefits and create a more complete documentation.
... In the case of WV-2, the overlapping between neighbouring bands, from 1 to 7 is negligible, and in the case of bands 7 and 8, only the tails of both bands overlap (Updike and Comp, 2010). The overlapping between bands in the case of the Canon Powershot S110 RGB and Canon Powershot S110 NIR cameras, is large (see the spectral profiles in Ref. SenseFly Ltd (2018b)), a typical characteristic of many digital cameras (Verhoeven, 2008;Berra et al., 2015). Moreover, the response of the NIR band of the Canon Powershot S110 NIR 11. ...
... Thus, the spectral resolution of the sensors along with the status of the vegetation, explains the poor performance of the visible and NIR cameras in detecting crop marks. The performance of modified cameras has been analyzed by several authors (Nebiker et al., 2016;Verhoeven, 2008;Berra et al., 2015;Verhoeven, 2007;Verhoeven et al., 2009). Verhoeven (2007) uses the NIR band of a modified Nikon D50 carried on a helikit and on a small plane to detect crop marks undetected by the non-modified camera. ...
Article
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Active and passive remote sensing sensors have been applied successfully in the detection of crop marks (vegetation with a different spectral reflectance compared to its surroundings) related with buried archaeological remains. However, the detection of such crop marks depends on the sensor used, the status of the cover and the algorithm applied on the data. Moreover, buried archaeological remains generally produce microrelief marks, which can be very difficult to detect. The purpose of this work is to demonstrate that the combined use of data from the multispectral orbital sensor WorldView-2 and RGB and near infrared cameras mounted on an Unmanned Aerial Vehicle (UAV) equipped with a Global Navigation Satellite System (GNSS) can be successfully applied to the detection of buried archaeological remains. Principal Component Analysis, the Normalized Difference Vegetation Index (NDVI) and a purposely proposed band combination were obtained from WorldView-2 data to detect crop marks. The cameras carried by the UAV provide a Real Color composite, the NDVI and a high precision Digital Surface Model. The methodology developed in this work consists of searching for locations that exhibit both crop and microrelief marks with a similar shape. The WorldView-2 NDVI and the normalized Digital Surface Model of the UAV are filtered. An Archaeological Binary Map is constructed, in which pixels with both NDVI and normalized elevation above corresponding threshold values are interpreted as susceptible of containing buried archaeological remains and are given the value of one, otherwise zero. One of the locations of the Archaeological Binary Map, with a very regular pattern, is subsequently surveyed with Ground Penetrating Radar to find a buried structure, the location and shape of which match perfectly those of the Archeological Binary Map.
... The visible light perceived by humans ranges from wavelengths of approximately 380-750 nm [19]. Absolute thresholds vary from person to person and according to viewing conditions. ...
... Wavelengths from approximately 10-380 nm are termed ultraviolet. The IR portion of the spectrum ranges from approximately 750 nm-1 mm, with near-infrared (NIR) ranging from 750-1400 nm [19]. Objects exposed to NIR radiation (such as from an alternate light source) absorb, reflect and transmit these photons to varying degrees [20]. ...
Article
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IR Reflective dyes and pigments are designed to make absorption in the visible region of the electromagnetic spectrum like the standard dyes but to reflect the Infra-Red region of the spectrum as a difference; which enables the items dyed with them to heat less for darker shades when exposed to sunlight. In this study, a standard acid dyestuff and an IR reflecting acid dyestuff are used on leathers produced with 4 different fatliquoring processes. They are finished with standard and IR reflective pigments respectively. Then reflection behaviors of the resulting leathers were measured with an IR spectrophotometer to visualize the working theory. Later, the fastness properties of leathers were tested to see if they are applicable to leather articles and resistant to wear. Spectrums showed that black IR reflective dyes and pigments stop absorbing and start reflecting light with wavelengths above 700 nm which results cooler leathers under solar radiation. Rubbing fastness results showed that leathers, treated with IR reflective dyes and pigments, had better results with a slight difference than other standard acid dyestuff groups, which proved the durability of this application during wearing. When different fatliquoring processes were compared, it was not seen significant differences in final colors, reflection properties, and rubbing fastness results.
... Besides, NIR scattering from vegetation also depends on how healthy the vegetation is [5]. Stressed vegetation due to exposure to CO 2 or chemicals behaves differently, see e.g., [24][25][26]. ...
... For example, a Wratten filter with a cut-on wavelength of around 580 nm was used in combination with the blue pixels to record NIR images (see also below when discussing halos and [31]). From an artistic point of view this is fine; from a scientific point of view, one must keep in mind that for the vast majority of camera sensors (e.g., [26,30,[32][33][34]), there is still a residual sensitivity of blue pixels in the range between 600 and 750 nm (see Fig. 7). Taking into account typical daylight spectra as light source, one may conclude that an image recorded with cut-on wavelength of 580 nm and blue pixels will most likely have at least 15% to 20% contribution of residual visible light and therefore the respective images do not constitute pure NIR photos. ...
Article
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Digital near-infrared photography opens up new observation possibilities and applications for atmospheric optics. We discuss necessary conditions and requirements for observing a variety of atmospheric optical phenomena in the infrared spectral range and report for the first time near-infrared photographs of 22° ring halos and inferior mirages. Our emphasis is on optical phenomena observable in the troposphere, excluding the large body of work addressing near-infrared airglow and aurora.
... The development of photogrammetry softwares, which are able to process pictures taken with general purpose cameras, has brought about a revolution in archaeological recording, which in conjunction with the appearance of UAVs (which can accurately follow pre-programed missions), has allowed archaeologists to produce accurate surveys and 3D models easily and quickly [11][12][13]. The high sensitivity of digital cameras to near infrared wavelengths makes them perfect for recording this part of the light spectrum [14][15][16][17]. The general development of Geographic Information System (GIS) allows the management of geographic information from old and new maps, aerial photographs, site surveys, orthomosaics, etc., making them easy to work with, and an invaluable tool in heritage protection and management [18]. ...
... Multi-and hyperspectral images have been successfully used to document architectural heritage [27], and to study small finds [14]. Remote sensing techniques and indexes have been used to identify buried archaeological remains, but at present there is no general consensus about which wavebands and indexes such as NIR, NDVI, SR, BAI, TCARI, red edge are better for enhancing the visibility of cropmarks [3,4,7,15,16,28]. ...
Article
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The Iter 34 (Antonine Itinerary XXXIV) is the name of the Roman road that crosses the province of Álava from west to east. Since no specific path was officially recognized before our study, the remains of the road did not benefit from heritage protection. In 2017, we made a project to determine the course of the road through rural Álava. In addition to traditional archaeological excavation and prospecting techniques, we used UAVs (unmanned aerial vehicle) to produce NDVI (normalized difference vegetation index) orthomosaic plans of ten cultivated areas through which the road is conjectured to pass. NDVI orthomosaics let us see crop marks better than with conventional photography, allowing us to detect the crop marks during times of the year and in places where conventional photography would fail to show them. Thanks to the NDVI orthomosaics, remains of the road were identified not only in places where we knew it existed, but also in previously unknown locations. Furthermore, other archaeological features were identified close to the roadway. This technique heralds a great advance in non-invasive methods of archaeological surveying. By using precision farming techniques we have identified the course of the Roman road Iter 34 in several locations in a short period of time and with few resources.
... Though stressors may include diseases or non-conducive soils, stress can also be caused by materials buried in the sediments. This has archaeological applications as it might suggest the presence and nature of archaeological features that might skew a plant's typical NIR signature (Verhoeven, 2008). ...
Thesis
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Archaeological investigation is an inherently destructive process that threatens permanent data loss if archaeological sites are inadequately recorded. While archaeologists strive to develop innovative methods to ensure adequate data capture, they are often inhibited by funding and training in new methodologies. Limited funding is exacerbated in a consulting archaeology framework in Ontario where budgets are competitively determined and offer little flexibility or incentive to exceed the minimum standards enforced by the Ministry of Tourism, Culture and Sport (MTCS). This thesis critically examines consumer-grade unmanned aerial vehicles (UAVs) as a potential site recording and prospecting tool. Through four case studies, the UAVs efficacy is evaluated and UAV-derived data products are outlined to determine whether the aerial platform is a suitable technological innovation that increases data capture while remaining affordable for Ontario consultant archaeologists.
... The resolution of these instruments is usually low, and the collected imagery has to be meticulously checked to correct sensors' errors [39,40]. The introduction, or rather repurposing, of commercial digital single-lens reflex (DSLR) cameras with charge-coupled device (CCD) and complementary metal-oxide-semiconductor (CMOS)-based detectors, for spectral imaging at the same range, however, provides more affordable and agile solutions that retain the user-friendly features and the interfaces to a wide variety of photographic software and accessories, and have high spatial resolution [41][42][43]. Commercial off-the-shelf (COTS) DSLR camera detectors are generally sensitive in a portion of the NIR range up to 1100 nm, which is cut off by an internal blocking filter. ...
Article
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The conservation of historic structures requires detailed knowledge of their state of preservation. Documentation of deterioration makes it possible to identify risk factors and interpret weathering mechanisms. It is usually performed using non-destructive methods such as mapping of surface features. The automated mapping of deterioration is a direction not often explored, especially when the investigated architectural surfaces present a multitude of deterioration forms and consist of heterogeneous materials, which significantly complicates the generation of thematic decay maps. This work combines reflec-tance imaging and supervised segmentation, based on machine learning methods, to automatically segment deterioration patterns on multispectral image composites, using a weathered historic fortification as a case study. Several spectral band combinations and image classification techniques (regression, decision tree, and ensemble learning algorithmic implementations) are evaluated to propose an accurate approach. The automated thematic mapping facilitates the spatial and semantic description of the deterioration patterns. Furthermore, the utilization of low-cost photographic equipment and easily operable digital image processing software adds to the practicality and agility of the presented methodology.
... In recent times, geomatics has become an essential tool in archaeology due to the advantages of these techniques in documenting and modelling heritage. With their application ranging from large archaeological sites (Gallo et al., 2009) to small artefacts (Evgenikou and Georgopoulos, 2015), geomatic techniques have undergone a great evolution in recent decades mainly due to the appearance and development of new acquisition techniques (e. g. remote sensing, aerial and terrestrial photogrammetry, Light Detection and Ranging [LiDAR], etc.) (Gallo et al., 2009;Campana, 2017;Chase et al., 2011), including new platforms for aerial surveying (using Unmanned Aerial Systems, masts, etc.) (Verhoeven, 2009;Mozas-Calvache et al., 2012a;Martínez et al., 2013;Ortiz et al., 2013), new acquisition sensors (e. g. laser scanners, cameras, etc.) (Lerma et al., 2010;Fiorillo et al., 2016), including non-visible wavelengths (Verhoeven, 2008) and the improvement of hardware and software applications for processing the data acquired. In this context, we can highlight some studies such as Remondino (2011) which described the main techniques and sensors used recently. ...
Article
This study describes a new procedure for acquiring images and developing photogrammetric studies of inaccessible spaces in archaeology. The approach is based on the acquisition of photographs using a system mounted on a mast, with a length of up to 4 m. The camera is handled using a remote control assisted with a real-time viewer. After the acquisition of images, a photogrammetric process is developed. As a result, we can obtain photogrammetric products such as orthoimages that can be used for several purposes, such as the documentation of the initial status of the scene, the identification of elements, the planning of future work, etc. The procedure has been applied successfully to several burial chambers discovered in the Qubbet el-Hawa site (Aswan, Egypt). Among other results, we can highlight the identification of the deceased buried in a narrow intact chamber, which was opened for a short period, and the determination of the geometric measurements of the coffin that were usable in subsequent work. Thanks to the orthoimage obtained in this study the deceased of the QH34bb tomb was identified as Shemai, brother of governor Sarenput II. The obtaining of metric products of inaccessible spaces provides an important base of documentation to be used by other researchers with the great advantage of not affecting the scene and allowing them to design appropriate methods of conservation.
... The use of RGB values can introduce a bias, since the RGB colour model is based on the human perception of colours, therefore not necessarily corresponding to the colour regions where the rock surface shows different behaviours. Nevertheless, this limitation can be in part overcome with the use of a converted full-spectrum (visible + NIr) photographic camera and one or more photographic blocking filters (Verhoeven, 2008). Albeit this consideration on application of GRIGRI model, this model may be used in a relative way on a global scarp in order to discuss the mapping of relatively younger-older scar. ...
Thesis
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La haute montagne est un terrain particulièrement sensible aux variations climatiques. La hausse de température depuis plusieurs décennies a un fort impact sur les parois du massif du Mont Blanc : la dégradation du permafrost s’y traduit par une activité gravitaire majeure. Une augmentation du nombre d'écroulements (>100 m3) liés à des périodes chaudes a en effet été mis en évidence à plusieurs échelles de temps, lors des étés particulièrement chauds de 2003 et 2015 comme au cours des trois dernières décennies. La fréquence des écroulements dans le massif devrait continuer à s’accroitre avec l’augmentation de la température au 21e siècle.En revanche, la fréquence des écroulements dans le massif antérieurement à la fin du Petit Âge Glaciaire (PAG) est très largement inconnue. Pendant l'Holocène voire le Tardiglaciaire, les écroulements dans le massif du Mont Blanc ont-ils également été favorisés par les hausses de température ? Pour répondre à cette question, cette thèse poursuit quatre objectifs :i.Dater un grand nombre d'écroulements dans la partie centrale du massif pour comprendre leur distribution pendant l'Holocène et le Tardiglaciaire. L'âge des niches d’arrachement est obtenu par datation cosmogénique.ii.Vérifier les possibles corrélations entre périodes à forte occurrence d’écroulements et périodes climatiques post-glaciaires.iii.Quantifier le volume des écroulements par reconstruction 3D de la forme des blocs écroulés, et étudier la relation entre volumes écroulés et périodes climatiques.iv. Etudier la relation entre âge d'exposition et couleur des niches d’arrachement quantifiée avec la spectroscopie de réflectance.Un total de 70 surfaces a été échantillonné dans les parois du massif au cours de trois campagnes de terrain en 2006, 2011, et 2015-2016. Les âges d'exposition de 63 surfaces ont été obtenus, compris entre 30 ± 20 ans et 100.50 ± 8.50 ka. Trois groupes d’âges peuvent être corrélés aux périodes climatiques chaudes que sont : les Périodes Chaudes de l'Holocène moyen (7.50 – 5.70 ka), l'Optimum de l'âge de Bronze (3.35 – 2.80 ka) et le Période Chaude Romaine (2.35 – 1.75 ka) ; un quatrième groupe d'âges est daté entre 4.91 et 4.32 ka. Le groupe d'âges le plus nombreux, entre 1.09 ka et l'Actuel, aux volumes généralement réduits, est interprété comme représentatif de l'activité gravitaire annuelle du massif avec le climat actuel.Les données spectrales des échantillons datés ont permis de développer un index de la couleur du granite (GRIGRI) par combinaison des valeurs de réflectivité de deux longueurs d'onde différentes. Cet index est corrélé avec l'âge d'exposition (R=0.861) ; il a permis de proposer la datation de 10 échantillons d'âge inconnu à partir de leurs caractéristiques spectrales.
... This drawback can be fixed using 3D photogrammetry and UV rendering starting from UVF images acquired with a traditional camera and processed with the Agisoft PhotoScan ® software (Agisoft LLC, St. Petersburg, Russia) [18][19][20]. IR photography is also commonly used in the documentation phase of the restoration process, especially for paintings, in order to detect underdrawings, pentimenti, hidden signatures, etc. [21][22][23]. On the other hand, this technique, to our knowledge, was never applied to sculptures in order to obtain 3D models under infrared radiation. ...
Article
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The aim of this work is to present a new practical approach to digital photogrammetry to obtain 3D models of polychromatic sculptures under ultraviolet fluorescence and near-infrared by starting from photographic images. This digital photogrammetry was applied recently to a 17th-century reliquary bust representing St. Rodonio, a saint particularly venerated by the Orthodox Church, presently under restoration in the Laboratories of University of Tuscia and belonging to the Museum of Colle del Duomo of Viterbo (Italy). The acquisitions of ultraviolet fluorescence and infrared frames were performed using a Nikon D5300 digital SLR camera and a modified low-cost digital camera (Samsung Model NX3300), respectively. The three-dimensional UV and IR models were obtained using Agisoft PhotoScan ® software. The generated ultraviolet 3D model of the bust makes visible, in a single file, the fluorescence induced by UV radiation on the entire sculpture, highlighting surface abrasions, organic dyes, and ancient protective features. The infrared 3D model allowed for better definition of the details of the drawing used for eyes, nose and mouth definition. In conclusion, the ultraviolet fluorescence and IR 3D models of Saint Rodonio were particularly useful as documentation tools for the conservation status and for the painting construction, allowing us to perfectly map the original and restoration materials and to detect the drawing in single dynamic 3D files following a totally non-invasive, cost-effective, and rapid approach.
... When material is photographed using infrared radiation there are three possible recording outcomes; (i) the material may absorb infrared radiation and become darker, (ii) the material may reflect infrared radiation and become lighter or, (iii) the material may transmit infrared radiation and become transparent [18]. Infrared photography requires infrared sensitive film or digital cameras suitable (or modified) for recording infrared and a light source containing infrared radiation [17][18][19][20]. ...
Article
Bloodstain evidence is an element of crime scene investigation often found at scenes involving violence. Setting fire to the scene is a method sometimes used by offenders of crime in an attempt to conceal evidence. Fire often produces thick soot as a by-product of the combustion and has the potential to cover bloodstain patterns rendering them latent. There is limited published material offering a method of detecting bloodstains hidden beneath dense soot deposits caused by fire. This project employed a modified digital single-lens reflex (SLR) camera to investigate the application of reflected infrared photography to detect latent bloodstain evidence beneath varying deposited overlaying soot densities. The potential of this technique was examined by photographing blood samples beneath soot from a scaled fire simulation. A qualitative evaluation was completed by comparing images taken of a series of samples using both reflected infrared and standard visible light photography and corroborated with quantitative image analysis to support the findings. Results indicate that infrared photography can reveal latent bloodstains beneath a dense layer of soot in excess of ρ2.3 (550nm) density with substantial clarity. The success of this technique is dependent on specific optical and specimen parameters. These parameters include (i) the reflective properties of the background surface, (ii) the spectral absorption properties of blood and (iii) the ability of infrared wavelengths to transmit through the soot layer. Reflected infrared photography may provide crime scene examiners with a specialised field recording method that is easily executed and non-destructive to assist in visualising and locating latent bloodstain patterns beneath dense layers of soot.
... After amplification, the voltage output of the pixel is transferred through a micro-wire at the output of the chip. [1,2,3,4,5,6] ...
Working Paper
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... Falco (2009) focused on the use of a modified camera for reflected IR imaging with examples of revealing underdrawings in paintings and distinguishing materials in a suit of armour. Verhoeven (2008) provided examples of the use of an IR modified camera for aerial archaeological imaging, ceramic sherds, and obscured writing and Verhoeven et al. (2009) presented its use as a flexible and low-cost approach for aerial archaeological reconnaissance. Webb (2017) used a modified camera for reflected IR imaging of three-dimensional objects investigating the potential integration of IR and 3D imaging for object documentation. ...
Conference Paper
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Spectral and 3D imaging techniques are used for museum imaging and cultural heritage documentation providing complementary information to aid in documenting the condition, informing the care, and increasing our understanding of objects. Specialised devices for spectral and 3D imaging may not be accessible for many heritage institutions, due to cost and complexity, and the modification of a consumer digital camera presents the potential of an accessible scientific tool for 2D and 3D spectral imaging. Consumer digital cameras are optimised for visible light, colour photography, but the underlying sensor is inherently sensitive to near ultraviolet, visible, and near infrared radiation. This research presents the characterisation of a modified camera to investigate the impact of the modification on the spectroradiometric and geometric image quality with the intention of the device being used as a scientific tool for cultural heritage documentation. The characterisation includes the assessment of 2D image quality looking at visual noise, sharpness, and sampling efficiency using the target and software associated with the Federal Agencies Digitization Guidelines Initiative. Results suggest that these modifications give rise to discrepancies in computed surface geometries of the order of ± 0.1 mm for small to medium sized objects used in the study and recorded in the round (maximum dimension 20 cm). Measuring the spectral response quantifies the modified camera as a scientific device for more accurate measurements and provides indications of wavelengths that could improve documentation based on sensitivity. The modification of a consumer digital camera provides a less expensive, high-resolution option for 2D and 3D spectral imaging.
... Such information can be accessed thanks to the penetrating power of IR radiations [40,[57][58][59][60]. In the SWIR range, the best contrast to visualize this particular underdrawing is obtained with the greyscale mapping of the reflectance factor at 1770 nm (Fig. 3b). ...
Article
In the last decade, Mesoamerican codices have been the subjects of numerous characterization studies. Due to their large sizes, a limited number of areas were effectively analyzed, but considered representative of the manuscripts material constituents. In order to overcome this necessary assumption, a complementary approach is presented here, with the use of macroscopic diffuse reflectance spectral imaging (also known as “hyperspectral” imaging), in the visible to short wave infrared range (400–2500 nm). It allowed to study the entire surface of the Codex Borbonicus, a 16th century Aztec manuscript, used as an example of application for our innovative methodology. Numerous types of information (colorimetric data, visualization of underdrawings, spectral segmentation and chemical mappings) were obtained, and the entire document material composition was examined. These new data enrich the current knowledge on traditional Mesoamerican manuscript manufacturing techniques. More importantly, this demonstrates the great potential of this approach for the non-invasive study of large polychromatic surfaces. For the first time, an entire manuscript is analyzed using this approach providing several types of information on the same document with a single analytical technique.
... Falco (2009) focused on the use of a modified camera for reflected IR imaging with examples of revealing underdrawings in paintings and distinguishing materials in a suit of armour. Verhoeven (2008) provided examples of the use of an IR modified camera for aerial archaeological imaging, ceramic sherds, and obscured writing and Verhoeven et al. (2009) presented its use as a flexible and low-cost approach for aerial archaeological reconnaissance. Webb (2017) used a modified camera for reflected IR imaging of three-dimensional objects investigating the potential integration of IR and 3D imaging for object documentation. ...
Article
Full-text available
Spectral and 3D imaging techniques are used for museum imaging and cultural heritage documentation providing complementary information to aid in documenting the condition, informing the care, and increasing our understanding of objects. Specialised devices for spectral and 3D imaging may not be accessible for many heritage institutions, due to cost and complexity, and the modification of a consumer digital camera presents the potential of an accessible scientific tool for 2D and 3D spectral imaging. Consumer digital cameras are optimised for visible light, colour photography, but the underlying sensor is inherently sensitive to near ultraviolet, visible, and near infrared radiation. This research presents the characterisation of a modified camera to investigate the impact of the modification on the spectroradiometric and geometric image quality with the intention of the device being used as a scientific tool for cultural heritage documentation. The characterisation includes the assessment of 2D image quality looking at visual noise, sharpness, and sampling efficiency using the target and software associated with the Federal Agencies Digitization Guidelines Initiative. Results suggest that these modifications give rise to discrepancies in computed surface geometries of the order of ± 0.1 mm for small to medium sized objects used in the study and recorded in the round (maximum dimension 20 cm). Measuring the spectral response quantifies the modified camera as a scientific device for more accurate measurements and provides indications of wavelengths that could improve documentation based on sensitivity. The modification of a consumer digital camera provides a less expensive, high-resolution option for 2D and 3D spectral imaging.
... During World War II, aerial photography was further developed, and the vertical and oblique photography technologies were greatly improved; color photography and color infrared photography were also invented (Thomas, 1945). The use of infrared and later multispectral photography in aerial archaeology in the 1970s increased the visible range so that differences in soil moisture and crop growth could be used more effectively (Estes, 1966;Rigaud and Herse, 1986;Verhoeven, 2008;Verhoeven, 2012). However, inherent conceptual issues such as survey bias (Lambers, 2018;Verhoeven and Sevara, 2016;Verhoeven, 2017) could not be resolved through technological innovation. ...
Article
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Archaeological and cultural heritage (ACH), one of the core carriers of cultural diversity on our planet, has a direct bearing on the sustainable development of mankind. Documenting and protecting ACH is the common responsibility and duty of all humanity. It is governed by UNESCO along with the scientific communities that foster and encourage the use of advanced non-invasive techniques and methods for promoting scientific research into ACH and conservation of ACH sites. The use of remote sensing, a non-destructive tool, is increasingly popular by specialists around the world as it allows fast prospecting and mapping at multiple scales, rapid analysis of multisource datasets, and dynamic monitoring of ACH sites and their surrounding environments. The cost of using remote sensing is lower or even zero in practical applications. In this review, in order to discuss the advantages of airborne and spaceborne remote sensing (ASRS), the principles that make passive (photography, multispectral and hyperspectral) and active (synthetic aperture radar (SAR) and light detection and ranging radar (LiDAR)) imaging techniques suitable for ACH applications are first summarized and pointed out; a review of ASRS and the methodologies used over the past century is then presented together with relevant highlights from well-known research projects. Selected case studies from Mediterranean regions to East Asia illustrate how ASRS can be used effectively to investigate and understand archaeological features at multiple-scales and to monitor and assess the conservation status of cultural heritage sites in the context of sustainable development. An in-depth discussion on the limitations of ASRS and associated remaining challenges is presented along with conclusions and a look at future trends.
... The research was undertaken mainly within the Potenza Valley Project in central Italy, a long-term collaboration that has been integrating a wide variety of research methodologies, including surface survey, geo-archaeological survey, geophysical prospection and archaeological excavation (Vermeulen et al., 2006). In this case the sensor was a standard SLR 289 Drones in Archaeology camera that had been modified to record the nearinfrared portion of the electromagnetic spectrum (Verhoeven, 2008). Overall, the results showed that the use of the differing bands, in combination, resulted in a considerable improvement in the visibility of the archaeological features, in some cases even allowing the recovery of traces that were otherwise completely invisible. ...
Article
In addition to traditional platforms for low-level remote sensing (balloons, kites, etc.) new and more complex automated systems [unmanned aerial vehicles (UAVs) or drones] have become available in the last decade. The success and market expansion of these platforms has been a driving force in the development of active and passive sensors specifically designed for UAVs. In the last few years archaeologists have started testing both platforms and sensors, particularly for the following applications: three-dimensional (3D) documentation of archaeological excavations; 3D survey of monuments and historic buildings; survey of archaeological sites and landscapes; exploratory aerial survey; and the archaeological survey of woodland areas. The scale of these applications has ranged from site-based to landscapes-based (approximately up to about 10 km2 in extent). The role of such platforms in the archaeological survey of excavations and landscapes, and in diagnostics more generally, is of great interest and is inexorably growing. Copyright
... Journal of Archaeological Science: Reports 27 (2019) 101941 used (cf. Verhoeven, 2008). Later on, quadrocopters with visible light cameras (RGB) were chosen (i. ...
... Las cámaras digitales comerciales son equipos de bajo costo y de fácil manejo que pueden ser empleados para fines científicos, como avalan diversos estudios (Akkaynak et al., 2014;Chakrabarti et al., 2009;Verhoeven, 2008), siempre que se salvaguarden unas condiciones de captura -formato de Aplicación de la fotografía métrica en edificación mediante el uso de la cámara digital … Application of metric photography in building using the conventional digital camera… la imagen, luminosidad y calibración de color-que garanticen una mínima distorsión de la escena. Para el registro de la estratigrafía se utilizó una cámara digital convencional réflex Canon EOS 450D, con sensor CMOS de 22,2 x 14,8 mm y con 12,2 megapíxeles efectivos. ...
Article
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ResumenEl análisis estratigráfico constituye una herramienta de diagnosis indispensable en obras de arqueología, que permite descifrar a arqueólogos, historiadores y antropólogos la disposición e interrelación entre los diferentes estratos y la ordenación cronológica de los restos hallados. En este campo, la fotogrametría realizada con cámara digital convencional y software de amplia difusión constituye una alternativa versátil, eficiente y asequible frente a las técnicas convencionales de representación, basadas en procedimientos artesanales y cargadas de subjetividad, cuyas principales limitaciones son analizadas. En este artículo se establecen una sencilla metodología y un modelo sistemático para la documentación y preservación de unidades estratigráficas en excavaciones arqueológicas, compatibles con la técnica de análisis estratigráfico basada en la matriz Harris. La validez y posibilidades del método han sido constatadas en el proyecto de intervención arqueológica desarrollado en la Capilla Real de la Catedral de Sevilla.AbstractThe stratigraphic analysis constitutes an essential diagnostic tool in archelogy works, which allows the archaeologists, historians and anthropologists to decipher the arrangement and interrelation between the different strata and the chronological ordering of the remains found. In this field, the photogrammetry realized with conventional digital camera and software of wide diffusion constitutes a versatile alternative, efficient and affordable in front of the conventional techniques of representation, based on artisan and loaded procedures of subjectivity, whose main limitations are analyzed. This article establishes a simple methodology and a systematic model for the documentation and preservation of stratigraphic units in archaeological excavations, compatible with the technique of stratigraphic analysis based on the Harris matrix. The validity and possibilities of the method have been verified in the project of archaeological intervention developed in the Royal Chapel of the Cathedral of Seville.
... By removing the internal near-infrared cut-off filter, a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS)-based camera can be used as an affordable and agile alternative for multispectral acquisition. Narrow or wideband external filters allow capturing reflectance data at the very near-infrared range, while the camera retains user-friendly features and interfaces to a wide variety of photographic accessories and software [173][174][175]. Adamopoulos and Rinaudo [167], Lerma et al. [168], Meroño et al. [169], and Sánchez and Quirós [176] have used this method to obtain visible and very near-infrared images aiming to identify weathering on historical stone buildings or masonry. ...
Article
Full-text available
Built cultural heritage is under constant threat due to environmental pressures, anthropogenic damages, and interventions. Understanding the preservation state of monuments and historical structures, and the factors that alter their architectural and structural characteristics through time, is crucial for ensuring their protection. Therefore, inspection and monitoring techniques are essential for heritage preservation, as they enable knowledge about the altering factors that put built cultural heritage at risk, by recording their immediate effects on monuments and historic structures. Nondestructive evaluations with close-range sensing techniques play a crucial role in monitoring. However, data recorded by different sensors are frequently processed separately, which hinders integrated use, visualization, and interpretation. This article’s aim is twofold: i) to present an overview of close-range sensing techniques frequently applied to evaluate built heritage conditions, and ii) to review the progress made regarding the fusion of multi-sensor data recorded by them. Particular emphasis is given to the integration of data from metric surveying and from recording techniques that are traditionally non-metric. The article attempts to shed light on the problems of the individual and integrated use of image-based modeling, laser scanning, thermography, multispectral imaging, ground penetrating radar, and ultrasonic testing, giving heritage practitioners a point of reference for the successful implementation of multidisciplinary approaches for built cultural heritage scientific investigations.
... Faster readout, low power consumption, higher noise immunity, and it is very sensitive to both visible as well as IR spectrum of light 5 . But the internal optical low pass filter which is placed in front of image sensor will block IR light and allow only visible light to pass through and reaches the image sensor 6 . This filter is removed and replaced by 35mm exposed photographic film and Kodak wratten IR filter to block visible light thus webcam becomes sensitive only to IR light. ...
Conference Paper
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This work presents a portable, affordable and reliable vein locating device to overcome the complications in vein localization irrespective of age and tissue thickness during medical procedures like Phlebotomy and intravenous infusion. A prototype has been developed using infrared (IR) detector and multispectral near infrared (NIR) (740,765,770,780 nm) source. The differential absorption of the NIR by veins due to the presence of deoxyhemoglobin, helps in enhancing the localization of the vein. The detector is integrated with the single board computer (SBC) and connected with LCD through serial programming interface (SPI) for real time display of veins. The initial observations have found to be successful. It is expected that this affordable device will help in reducing time and improving accessibility to locate antecubital and cephalic vein without multiple incision and minimal pain.
... There are applications in industry and science across the UV, visible and NIR wavelength range that can benefit from a high brightness capability, high security, linear irradiance extraction, moderately HDR (e.g., > 60 dB), robust SNR, full spectrum (e.g., 350 nm to 1800 nm) operations camera unit [1][2][3][4][5][6]. Most deployed camera systems use multiple image sensors, e.g., silicon CCD, silicon CMOS and InGaAs IR Focal Plane Array (FPA) direct pixel readout sensors along with multiple wavelength filters and optics to realize a multispectrum imaging system [7]. ...
Preprint
For the first time, the hybrid triple coding empowered Frequency Division Multiple Access (FDMA) Code Division Multiple Access (CDMA) mode of the CAOS (i.e., Coded Access Optical Sensor) camera is demonstrated. Compared to the independent FDMA and CDMA modes, the FDMA-CDMA mode has a novel high security space-time-frequency triple signal encoding design for robust, faster, linear irradiance extraction at a moderately High Dynamic Range (HDR). Specifically, this hybrid mode simultaneously combines the linear HDR strength of the FDMA mode Fast Fourier Transform (FFT) Digital Signal Processing (DSP)-based spectrum analysis with the high Signal to Noise Ratio (SNR) provided by the many simultaneous CAOS pixels photodetection of the CDMA mode. In particular, the demonstrated FDMA CDMA mode with P FDMA channels provides a P times faster camera operation versus the equivalent linear HDR Frequency Modulation (FM)CDMA mode. The active FDMA CDMA mode CAOS camera operation is also demonstrated using P equal to 3 LED light sources, each with its unique optical spectral content driven by its independent FDMA frequency. This illuminated target spectral signature matched active CAOS mode allows simultaneous capture of P images without the use of P time multiplexed slots operation tunable optical filter.
... After amplification, the voltage output of the pixel is transferred through a micro-wire at the output of the chip. [1,2,3,4,5,6] ...
... Most modern cameras come with an infrared cut-off filter behind the lens to get the maximum amount of visible light for high-resolution images. This filter blocks wavelength above 700 nm in the electromagnetic spectrum, and it must be replaced with a filter that allows infrared radiation to be visible to the camera [32]. Hence, the camera is modified by replacing the infrared cut-off filter with another filter. ...
Article
Full-text available
Vein detection is an important issue for the medical field. There are some commercial devices for detecting veins using infrared radiation. However, most of these commercial solutions are cost-prohibitive. Recently, veins detection has attracted much attention from research teams. The main focus is on developing real-time systems with low-cost hardware. Systems developed to reduce costs suffer from low frame rates. This, in turn, makes these systems not suitable for real-world applications. On the other hand, systems that use powerful processors to produce high frame rates suffer from high costs and a lack of mobility. In this paper, a real-time vein mapping prototype using augmented reality is proposed. The proposed prototype provides a compromised solution to produce high frame rates with a low-cost system. It consists of a USB camera attached to an Android smartphone used for real-time detection. Infrared radiation is employed to differentiate the veins using 20 Infrared Light Emitting Diodes (LEDs). The captured frames are processed to enhance vein detection using light computational algorithms to improve real-time processing and increase frame rate. Finally, the enhanced view of veins appears on the smartphone screen. Portability and economic cost are taken into consideration while developing the proposed prototype. The proposed prototype is tested with people of different ages and gender, as well as using mobile devices of different specifications. The results show a high vein detection rate and a high frame rate compared to other existing systems.
... 439full-spectrum (visible + NIr) photographic camera and photographic blocking filters(Verhoeven, 2008). ...
Article
In the high mountain rock walls of the Mont Blanc massif, changes in the granite surface colour are related to its exposure age. The light grey colour of fresh rock surfaces turns orange when is long exposed to weathering. In order to study this colour/age relationship, reflectance spectroscopy was performed on 73 samples, and Terrestrial Cosmogenic Nuclide (TCN) dating was used to obtain their surface exposure age. The standard deviation of the reflectance values was calculated for each wavelength of the visible spectrum to study the behaviour of each spectral region. The aim was to find two colour regions that showed opposite behaviour, and once they are combined, they could provide a representative index of the rock colour changes that are linked to the degree of weathering. As an adaptation of the Green Red Vegetation Index used to measure colour changes in vegetation, the GReen-Infrared GRanite Index (GRIGRI), a normalized difference between the granite 770 nm and 530 nm reflectance values, was developed. The GRIGRI value of a weathered granite surface has a close relationship with its exposure age (R2=0.85). The reflectance spectra of seven samples for which TCN dating failed and two samples for which the TCN age was considered to be an outlier were used to calculate their GRIGRI value to assess the colour-based ages, that were plausible according to rock wall morphology and the TCN exposure ages of the surrounding surfaces. We propose a new method of surface dating for the rock walls of the Mont Blanc massif using reflectance spectroscopy.
... [74] The EM waves humans perceive -the so-called visible light -encompasses a very small portion of all EM radiation: only wavelengths between approximately 380 nm and 750 nm. [74] This takes into account the absolute thresholds varying from person to person and specific viewing conditions. However, on both sides of this extremely small visible spectrum resides EM radiation the HVS is insensitive for, characterized by wavelengths smaller than 380 nm or larger than 750 nm. ...
Article
Where exactly is the "true" Mount Sinai? Is it at the romanticized popularized location made by the controversial amateur archaeologist the late (Ron Wyatt). Who first proposed "Mount Sinai was in Saudi Arabia". [Ronald Stewart]-(Author of this volume #1), shall present and demonstrate Scripural, known and unknown new scientific, (AM)-(Angstrom-Microscope)-Scientific Application, microscopic, geological, volcanology, mineral, chemical, elemental, geographical, topographical, lost historical, archaeological, (biblical archaeological-including: "Pre-Hebrew-Writing-Petroglyph-Depictions"), photographic, cross-comparison-photographic, and other various forms of evidence, provide an abundant wealth of new in-depth comprehensive diagnosis and analysis data and evidnce. Not only questioning, the beliefs, statements, and claims, made by the proponents, that the (Jabbal-el-Lawz) and especially that the (Jabal-el-Maqla) mountain sites are the true biblical Mount Sinai in (NW)-(northwestern) Saudi Arabia. But rather, that the true biblical Mount Sinai but is not in (NW)-(northwestern) Saudi Arabia, but that the aforementioned abundant wealth of new data and evidence will support, uphold, and defend, that the true biblical Mount Sinai and the culmination of the events of the Israelite Exodus took place rather at (Jebel-Musa). Which is today's accepted traditional location for the true biblical Mount Sinai instead.
... HERE are numerous applications in industry and science across the UV, visible and NIR wavelength range that can benefit from a linear HDR (e.g., > 60 dB) robust SNR full spectrum camera [1][2][3][4][5][6]. Most deployed camera systems use multiple image sensors, e.g., silicon CCD, silicon CMOS and GaAlAs IR Focal Plan Array (FPA) sensors along with multiple wavelength filters and optics to realize a multi-spectrum imaging system. ...
Preprint
For the first time, the hybrid Frequency Division Multiple Access (FDMA) Code Division Multiple Access (CDMA) mode of the CAOS (i.e., Coded Access Optical Sensor) camera is demonstrated. The FDMA CDMA mode is a time frequency double signal encoding design for robust and faster linear High Dynamic Range (HDR) image irradiance extraction. Specifically, it simultaneously combines the strength of the FDMA-mode linear HDR Fast Fourier Transform (FFT) Digital Signal Processing (DSP) based spectrum analysis with the CDMA mode provided many simultaneous CAOS pixels high Signal to Noise Ratio (SNR) photo-detection. The FDMA CDMA mode with P FDMA channels provides a faster camera operation versus the linear HDR Frequency Modulation (FM) CDMA mode. Visible band imaging experiments using a Digital Micromirror Device (DMD) based CAOS camera demonstrate a P equal to 4 channels FDMA CDMA mode high quality image recovery of a calibrated 64 dB 6 patches HDR target versus the CDMA and FM CDMA CAOS modes that limit dynamic range and speed, respectively. Simultaneous dual image capture capability of the FDMA-CDMA mode is also demonstrated for the first time in Ultraviolet (UV) to Near Infrared (NIR) 350 to 1800 nm full spectrum using Silicon (Si) and Germanium (Ge) point photo-detectors.
... Other events unrelated to war also contributed strongly to the development of remote sensing. For example, in 1942 the first (false-) color film, sensitive to infrared radiation was patented by Kodak [42], and prior to that, the first photograph of the curvature of the Earth was taken in 1936 by Albert W. Stevens [41]. ...
Chapter
Environmental monitoring is essential to prevent future problems in human health that may arise and to promote the sustainable development of societies. Indoor/outdoor environments have been monitored through analytical chemistry. Analytical techniques are mainly used for the detection of emerging contaminants, but these techniques have restrictions for their use in large analysis areas. Remote sensing can complement those standard analytical techniques for environmental analysis by obtaining a quick, sensitive, and decentralized measurement to respond appropriately to contingency scenarios. This chapter describes remote sensing from basic concepts to innovative applications in environmental monitoring and future perspectives.
... TP includes a wide range of techniques applicable to historic art examination [15]. Specifically, near-infrared (NIR) imaging has been implemented to enhance archaeological observation [16], to determine the state of conservation of buildings [17], to inspect mural paintings [18], to assist the identification of pigments [19], to investigate underdrawings of panel paintings [20], underprintings [21], and palimpsests [22], to examine rock art [23], and to study feature characteristics of painted artifacts [24]. Applications of integrated heritage CRP and TP can be found in recent bibliography, showcasing a promising combination that should be further evaluated. ...
Article
Full-text available
Passive sensors, operating in the visible (VIS) spectrum, have widely been used towards the trans-disciplinary documentation, understanding, and protection of tangible cultural heritage (CH). Although, many heritage science fields benefit significantly from additional information that can be acquired in the near-infrared (NIR) spectrum. NIR imagery, captured for heritage applications, has been mostly investigated with two-dimensional (2D) approaches or by 2D-to-three-dimensional (3D) integrations following complicated techniques, including expensive imaging sensors and setups. The availability of high-resolution digital modified cameras and software implementations of Structure-from-Motion (SfM) and Multiple-View-Stereo (MVS) algorithms, has made the production of models with spectral textures more feasible than ever. In this research, a short review of image-based 3D modeling with NIR data is attempted. The authors aim to investigate the use of near-infrared imagery from relatively low-cost modified sensors for heritage digitization, alongside the usefulness of spectral textures produced, oriented towards heritage science. Therefore, thorough experimentation and assessment with different software are conducted and presented, utilizing NIR imagery and SfM/MVS methods. Dense 3D point clouds and textured meshes have been produced and evaluated for their metric validity and radiometric quality, comparing to results produced from VIS imagery. The datasets employed come from heritage assets of different dimensions, from an archaeological site to a medium-sized artwork, to evaluate implementation on different levels of accuracy and specifications of texture resolution.
... The remarkable speed and image quality of aerial imagery obtained from such increasingly low-cost solutions make the latter platforms potent instruments for reconnaissance. They have also allowed and stimulated the further exploitation of new imaging techniques, such as close-range near-infrared photography (Verhoeven, 2008(Verhoeven, , 2012 and near-ultraviolet imaging (Verhoeven & Schmitt, 2010;Verhoeven, Smet, Poelman, & Vermeulen, 2009). The now more readily available software solutions to orthorectify these oblique images (e.g. ...
Article
Over the past 15 years the Potenza Valley Survey project investigated Iron Age to Medieval settlement dynamics in the Central Adriatic Potenza Valley. Part of this research focuses on the Roman abandoned towns of Potentia and Trea by performing an integrated geoarchaeological study of their townscape. This largely noninvasive research consists of remote sensing analysis, geophysical surveys (magnetometry, electrical resistivity, and ground-penetrating radar), and geomorphological fieldwork such as microtopographic measurements and hand augering. The chosen techniques depend on the nature of each town and are integrated with more traditionally achieved research data. This paper presents the main interdisciplinary results of work on these two Roman towns and highlights the importance of obtaining complementary data and performing hand augering as a stratigraphic control of the remote sensing and geophysical results. Insights into the character and layout of the cities, the structural influence on the surrounding area, and the human-environment interactions and dynamics through time of both Roman cities could be achieved. Moreover, the results offer guidelines for conservation strategies of these abandoned towns and their suburbium, which are necessary to protect them from present-day threats such as agriculture and tourism. In this way the paper offers an insight in the tremendous potential of well-integrated geoarchaeological investigations of partly or fully abandoned urban contexts in the Mediterranean area and beyond.
... Although the value for archaeological survey of near infrared imagery and near infrared-derived vegetation indices such as NDVI (Normalized Difference Vegetation Index), has long been known and applied to satellite imagery [20][21][22] a new generation of affordable, lightweight near infrared sensors designed for low elevation drone-based imaging have recently become available. While archaeologists wishing to record low-elevation, multi-spectral data had previously been limited to custom modified visible light cameras [23,24], recently developed specialized multi-spectral sensors like the MicaSense RedEdge series, the Parrot Sequoia, the Sentera Quad Sensor, the Mapir Kernel, and the Slantrange 3p can now record individual spectral bands as separate images and are specifically designed for integration with commercial drones. Cheaper commercial multi-spectral options exist as well, like the Mapir Survey 3 and Agrocam Geo NDVI, which are more similar to the older DIY options and record multiple spectral bands on a single RGB (red, green, blue) sensor that has been specially filtered to record narrower bands that include the near infrared. ...
Article
Full-text available
While archaeologists have long understood that thermal and multi-spectral imagery can potentially reveal a wide range of ancient cultural landscape features, only recently have advances in drone and sensor technology enabled us to collect these data at sufficiently high spatial and temporal resolution for archaeological field settings. This paper presents results of a study at the Enfield Shaker Village, New Hampshire (USA), in which we collect a time-series of multi-spectral visible light, near-infrared (NIR), and thermal imagery in order to better understand the optimal contexts and environmental conditions for various sensors. We present new methods to remove noise from imagery and to combine multiple raster datasets in order to improve archaeological feature visibility. Analysis compares results of aerial imaging with ground-penetrating radar and magnetic gradiometry surveys, illustrating the complementary nature of these distinct remote sensing methods. Results demonstrate the value of high-resolution thermal and NIR imagery, as well as of multi-temporal image analysis, for the detection of archaeological features on and below the ground surface, offering an improved set of methods for the integration of these emerging technologies into archaeological field investigations.
... Such information can be accessed thanks to the penetrating power of IR radiations [40,[57][58][59][60]. In the SWIR range, the best contrast to visualize this particular underdrawing is obtained with the greyscale mapping of the reflectance factor at 1770 nm (Fig. 3b). ...
Chapter
(Full text available at https://hdl.handle.net/1887/57483) Remote sensing has a long and successful track record of detecting and mapping archaeological traces of human activity in the landscape. Since the early twentieth century, the tools and procedures of aerial archaeology evolved gradually, while earth observation remote sensing experienced major steps of technological and methodological advancements and innovation that today enable the monitoring of the earth’s surface at unprecedented accuracy, resolution and complexity. Much of the remote sensing data acquired in this process potentially holds important information about the location and context of archaeological sites and objects. Archaeology has started to make use of this tremendous potential by developing new approaches for the detection and mapping of archaeological traces based on digital remote sensing data and the associated tools and procedures. This chapter reviews the history, tools, methods, procedures and products of archaeological remote sensing and digital image analysis, emphasising recent trends towards convergence of aerial archaeology and earth observation remote sensing.
Conference Paper
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The aim of this research paper is to analyze occupational risk-prevention training in Small and Medium Enterprises (SMEs) in the Spanish Construction Sector. To do so, an in-depth study is completed on compliance with the entrepreneurial obligation to inform and to train workers in occupational risk-prevention. Three questionnaires were designed and two discussion groups were organized with risk-prevention trainers and business representatives in the sector. Databases from various bodies were jointly consulted, specifically the External Prevention Services (EPS) and the Construction Labour Foundation (CLF). The strategic indicators of training in risk-prevention were analyzed, such as the professional qualifications of the trainers, the training methodologies employed and the training and information that the worker received on the job. The results showed that the majority of trainers in charge of training courses were not construction specialists, the training courses were not adapted to the training level of the workers and, importantly, the teaching materials were never in the other languages of the foreign workers. Higher levels of professionalization are necessary for more effective and efficient training.
Article
With the development of imaging devices and image processing algorithms, numerous features have come to be used for the estimation of total nitrogen content (TNC) in plants. However, higher-dimensional inputs contain more correlated variables that can detrimentally affect model performance. In this study, a hybrid feature selection approach was developed for TNC estimation in Aquilaria sinensis. A low-cost modified digital camera with external filters was used to capture canopy images. Three feature selection methods, namely, random forest (RF), Pearson correlation coefficient (PCC)-based feature selection, and sequential backward selection (SBS), were combined into two hybrid feature selection algorithms (RF_SBS and PCC_SBS). In addition, three regression algorithms were used in hybrid feature selection process: random forest regression (RFR), support vector regression (SVR), and partial least squares regression (PLSR). The hybrid feature selection process consists of two steps. First, the lowest number of dimensions is sought based on the feature ranking. Then, SBS is used to find the best feature combinations. Compared with the original models, the R² values of the RF-SBS-based models are improved by 0.094 (RF_SBS_RFR), 0.190 (RF_SBS_SVR), and 0.116 (RF_SBS_PLSR), while the R² values of the PCC-SBS-based models are improved by 0.055 (PCC_SBS_RFR), 0.092 (PCC_SBS_SVR) and 0.128 (PCC_SBS_PLSR). Finally, the two best TNC estimation models are found to be PCC_SBS_PLSR, with an R² of 0.863, and RF_SBS_SVR, with an R² of 0.872. The proposed hybrid feature selection approach not only has great capacity to improve estimation accuracy but also can reduce model complexity by choosing the best feature subset.
Conference Paper
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Occupational risk-prevention implementation and its integration in the management systems of Small and Medium Enterprises (SMEs) are studied in the Spanish Construction Sector, through an analysis of data collected from a sample of 106 firms (SMEs) in the Autonomous Community of Castile-La Mancha (Spain). The following data-collection techniques were used: surveys, open questions, closed questions, and dichotomous questions. Qualitative Focus-Group techniques were chosen, to contrast the information, in view of the experts in the Construction Sector. Participants included risk-prevention experts from the public administrations. The results point to difficulties with the integration of Occupational Risk Prevention (ORP) in the Management Systems of SMEs in the Spanish construction sector, outside the corporate structure of the firm.
Book
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CITE nació en 2016 con el objetivo de favorecer la transferencia de conocimiento sobre aprendizaje, innovación y competitividad entre ámbitos productivos y formativos, así como dar a conocer mejores prácticas sobre innovación en formación y aprendizaje en el sector de la edificación. Así mismo, el congreso ha actuado como punto de encuentro entre distintos agentes sociales relacionados con la formación, a fin de fomentar la cooperación entre sus participantes y extenderla a otros ámbitos relacionados con el aprendizaje, la innovación y la competitividad en dicho sector. El programa CITE 2018 está estructurado en conferencias invitadas, mesas redondas, comunicaciones orales, posters y talleres sobre la base de diferentes áreas temáticas, tales como materiales y sistemas constructivos, prevención y seguridad eficiencia energética, domótica, rehabilitación, mantenimiento y patología en edificación, experiencias en innovación tecnológica en edificación. Destacar y agradecer el alto grado de participación en las anteriores ediciones, esperando que el éxito se repita en ediciones sucesivas y que ha supuesto en la actual edición, la presentación de más de 140 ponencias, 60% de las cuales corresponden a comunicaciones orales y el 40% restante a formato poster y virtual. Y finalmente agradecer, así mismo, la inestimable colaboración de la Cátedra-Empresa Proiescón.
Article
Locating the subtle and uneven deposition of human activities across the landscape continues to challenge archaeologists. Existing tools (e.g. excavation, shovel testing, pedestrian survey, and terrestrial geophysics) have proven effective at locating many types of archaeological features but remain time-consuming and difficult to undertake on densely vegetated or topographically complex terrain. As a result of these limitations, key aspects of past communities remain largely outside of archaeological detection and interpretation. This flattening of past lifeways not only affects broader understandings of these communities, but can also negatively impact the preservation of archaeological sites. This paper presents the detection of archaeological features through an analysis of drone-acquired thermal, multispectral, and visible light imagery, alongside historical aerial photography, in the area surrounding Middle Grant Creek (11WI2739), a late prehistoric village located at Midewin National Tallgrass Prairie in Will County, IL. Our investigations discovered a probable housing area and a ritual enclosure, increasing the area of the site from 3.4 ha to 20 ha. The proposed housing and ritual areas of this village also help contextualize finds from the ongoing archaeological excavations at Middle Grant Creek. More broadly, results demonstrate the valuable contributions that these relatively new archaeological survey methods have in shaping our understandings of the archaeological landscape and highlight the importance of integrating them into the archaeological toolkit.
Article
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his paper adresses the study of archaeological remains – located in «monte de La Sarda», between Alcalá de Gurrea and Gurrea de Gállego – which, ac-cording to their physical characteristics and geogra-phic location, could be identified as a section of the Osca – Caesaraugusta Roman road «De Italia in His-panias» – «Ab Asturica Terracone» of the Antonine Itinerary (Hispania Tarraconensis). The information obtained from the written medieval sources indi- cates that this road remained in use until the Arago-nese conquest at the end of the 11th century. Further-more, it shows it suffered a partial change in its route around Almudévar in 1170, by royal order; therefore, these archaeological remains could belong to that section of the mentioned Roman road. To confirm this assumption, we have used remote sensing by means of low altitude multispectral and thermal imagery with a fixed-wing drone.
Chapter
Determination of oxidation demand has been of interest to scientists for around 150 years. Various methods have been developed to determine chemical (COD) as well as biochemical oxygen demand (BOD). Numerous challenges, particularly interference with respect to COD and time of determination in the case of BOD, has always inspired scientists to develop analytical methods that can provide accurate results in a time-bound manner. Furthermore, real-time analysis of these parameters has also caught the attention of the research fraternity. In the last two decades, we have witnessed an increased use of instrumentation to overcome many issues related to the determination COD and BOD, which made it possible to carry out analysis in environmental and industrial set-ups as well as online monitoring.
Article
El presente artículo versa sobre el uso de la fotografía infrarroja transmitida (IRT), una técnica todavía muy desconocida, pese a que paradójicamente aporta una información fundamental en el estudio y documentación de las pinturas sobre lienzo. A diferencia de la fotografía infrarroja (IR), esta técnica opera por transmisión y no por reflexión, por lo ofrece imágenes transversales de todos los estratos de la obra. Fundamentalmente arroja evidencias sobre el diseño y la composición, visibilizando sus cambios; el método de ejecución empleado; pesquisas sobre los materiales; y evidencias del estado de conservación, pudiendo considerarse una de las técnicas más ricas de imagen multi-banda; procedimiento que además puede realizarse con escasa inversión. El objetivo de este artículo es darla a conocer para fomentar su uso entre conservadores e investigadores, así como mostrar ejemplos de sus aportaciones, ofreciendo claves de lectura para su correcta interpretación.
Article
For the first time, to the best of our knowledge, the hybrid triple coding empowered frequency division multiple access (FDMA)-code division multiple access (CDMA) mode of the coded access optical sensor (CAOS) camera is demonstrated. Compared to the independent FDMA and CDMA modes, the FDMA-CDMA mode has a novel high-security space-time-frequency triple signal encoding design for robust, faster, linear irradiance extraction at a moderately high dynamic range (HDR). Specifically, this hybrid mode simultaneously combines the linear HDR strength of the FDMA-mode fast Fourier transform (FFT) digital signal processing (DSP)-based spectrum analysis with the high signal-to-noise ratio (SNR) provided by the many simultaneous CAOS pixels' photodetection of the CDMA mode. In particular, the demonstrated FDMA-CDMA mode with P FDMA channels provides a P times faster camera operation versus the equivalent linear HDR frequency modulation (FM)-CDMA mode. Visible band imaging experiments using a digital-micromirror-device-based CAOS camera operating in its passive light mode demonstrates a P=4 channels FDMA-CDMA mode, illustrating high-quality image recovery of a calibrated 64 dB six-patch HDR target versus the CDMA and FM-CDMA CAOS modes, which limit dynamic range and speed, respectively. For the first time to our knowledge, we demonstrate the simultaneous dual image capture capability of the FDMA-CDMA mode using silicon (Si) and germanium (Ge) large-area point photodetectors, allowing the capture of the ultraviolet-near-infrared 350-1,800 nm full spectrum. The active FDMA-CDMA mode CAOS camera operation is also demonstrated using P=3 LED light sources, each with its unique optical spectral content driven by its independent FDMA frequency. This illuminated target spectral signature matched active CAOS mode allows simultaneous capture of P images without the use of P time-multiplexed slot operation tunable optical filters. Applications for such a FDMA-CDMA camera includes controlled light illumination food inspection to bright light exposure security systems.
Thesis
Au cours de cette recherche, nous avons contribué à l’étude et à la caractérisation des pigments utilisés par le peintre français Étienne Dinet à l’aube du XXe siècle. Notre approche a consisté à nous appuyer sur les manuels de peinture écrits par le peintre (Les fléaux de la peinture) dans lesquels il expose sa recherche des matériaux à utiliser en peinture. En nous basant sur ces écrits, nous avons créé une base de données de photographies scientifiques et de spectres de réflectance (visible et proche infrarouge) pour pouvoir déterminer les pigments employés dans ses tableaux. Sept tableaux ont ensuite étudié. L’imagerie scientifique nous a permis de caractériser la palette du peintre, en particulier lorsque nous avons eu la possibilité d’associer plusieurs techniques d’analyse produisant des données complémentaires. Nous avons ainsi montré l’intérêt d’employer simultanément un ensemble de techniques non invasives d’imagerie pour la caractérisation des pigments : aucun prélèvement de matière picturale n’est nécessaire et la faible quantité de lumière irradiant l’œuvre durant les mesures n’affecte pas sa conservation. La photographie technique peut fournir de nombreuses informations sur l’état de conservation d’une peinture et nous permet de détecter les interventions de restaurations effectuées au cours du temps. Elle nous permet aussi de formuler des hypothèses sur la palette du peintre. Pour confirmer ces hypothèses, il est nécessaire d’effectuer des analyses comme la fluorescence des rayons X et l’imagerie hyperspectrale, qui fournissent des informations plus précises et dont l’interprétation est plus certaine.
Research
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This represents one of several sections of "A Bibliography Related to Crime Scene Interpretation with Emphases in Geotaphonomic and Forensic Archaeological Field Techniques, Nineteenth Edition" (The complete bibliography is also included at ResearchGate.net.). This is the most recent edition of a bibliography containing resources for multiple areas of crime scene, and particularly outdoor crime scene, investigations. It replaces the prior edition and contains approximately 10,000 additional citations. As an ongoing project, additional references, as encountered, will be added to future editions. Perhaps no aspect of crime scene documentation is more important and more demonstrable than photography. The mere press of a button can lock in time a theoretically unbiased account of a scene or subject. How often have we experienced, or heard of, cases successfully resolved and adjudicated with the inclusion of accurate and complete photographs? Most investigators have also experienced the opposite situation in which too few, or poor, quality photographs are taken of a scene. For the analyst, jurist and jury person who have not had the opportunity to be at the crime scene as it was found by the investigator, photographs or videos may be the only remaining means of observing the condition of remains and environmental factors which may have affected their state. Most forensic anthropologists can relate personal horror stories of remains brought or shipped to their laboratories with little or no contextual record. Photographs of the original position of remains in their discovered context at the scene can be invaluable in such situations. An often used adage in police investigations is “film is cheap,” meaning that one can never take too many pictures of the crime scene, its contents, and its environs. Digital photographic technology advances each year with the increased ability to take more and better detailed pictures using adequate equipment affordable to most law enforcement. Smartphones now have cameras with more pixel capacity than some sole-functioning cameras. It is inexcusable for investigators to leave a crime scene without a good photographic record. Having said that, investigators must also realize that photography is but one part of a documentation trilogy. Accurate crime scene reconstruction is best served by incorporating good photography with good diagramming or mapping, and good note taking. The three not only act as checks on the others, but also fill each other's shortcomings. For example, photographs represent a perspective and can be affected by things such as parallax. Diagrams are limited by their schematic nature; notes by their lack of visual depictions. In concert, this trilogy of documentation techniques most completely preserves and describes a scene that is temporary in time and space. This bibliography devotes an entire category to photography and photogrammetry - The art or process of surveying or mapping via photographs, and usually aerial photographs. Several references to photogrammetric mapping may also be found in “Planning, Reconnaissance, Surveys, and Mapping Techniques”. This section of the bibliography may also include occasional references to remote sensing and satellite imagery as they utilize photogrammetry. Those citations may be cross-referenced to the section on Geophysical/Remote Sensing Technology and Applications. For more sources related to remote sensing, the reader is directed to that section.
Poster
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Since the astronomer and composer Sir Frederick William Herschel (1738-1822) discovered in 1800 the infrared portion of the electromagnetic spectrum, many other scientists became interested in this kind of invisible radiation. It lasted, however, until 1904 for the first near-infrared photograph to be taken. From the 1930s onwards, this unusual type of imaging was practised more elaborately, specifically to examine damaged and censored writings or study blood patterns for medical purposes. After 1935 – the year in which one of the earliest infrared aerial photographs was taken from a stratosphere balloon – the trend was set. Less than a decade afterwards, aerial infrared colour film became extensively used for its camouflage detection capabilities in WWII. Today, orbital and aerial NIR recording serves a great number of applications, being intensively used by the military as well as the scientific fields of hydrology, geology, forestry and archaeology. Up till now, NIR radiation was mostly captured in an analogue way by infrared sensitive plates or film emulsions (black-and-white or colour), or digitally by satellites or high-tech multispectral sensors. For various reasons (cost, resolving power, lack of hardware etc.), aerial archaeologists use(d) the analogue NIR approach to study their objects (some examples are – amongst others – the work of Bradford, Strandberg, Solecki, Edienne and Martin). Such a film-based workflow is however very error-prone, as the emulsions need to be stored cooled and developed by specialised labs directly after exposing them. Moreover, determining the right exposure is not as straightforward as with conventional/standard (i.e. visible light) photography. Together with some ignorance and/or lack of knowledge about the subject, this critical imaging process severely restricted NIR radiation to be captured by aerial archaeologists so far. However, this changed completely with the advent of digital cameras. As their sensors are very sensitive to NIR radiation, the whole process of taking NIR photographs is much less of a cumber stone. The poster under consideration wants to show how NIR imagery can be taken with normal (and converted) digital cameras, what the images look like, compare the advantages (and disadvantages) to normal aerial imaging (e.g. haze penetration, enhanced clarity of detail and visualization of stressed vegetation) as well as outline a basic approach of NIR image processing.
Article
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Here is a new application of infra-red photography with a digital camera to record rock art. The need to make full and accurate records of the images, without touching (and thus degrading) the rock, requires a method of remote mapping. Trials with digital IR reported here are very promising and especially useful for painted rock art.
Article
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Using data collected by NASA in the Tehuacan Valley, Mexico, tests were undertaken to determine the effectiveness of aerial color infrared film for archaeological reconnaissance. The study area was chosen primarily because MacNeish's Tehuacan Archaeological-Botanical Project (1960-1964) provided a convenient check of site visibility on the photographs, and because microenvironmental zones have been delineated in the valley allowing visibility of sites in different microenvironments to be determined. Our tests indicate that the type of cultural feature or its age are not as important as the environmental situation in distinguishing the site. The greatest archaeological value, however, of color infrared photography is in the delineation of microenvironmental zones and the construction of natural maps rather than the identification of cultural features.
Article
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... Work done with G . Bearman and other physi- cists at NASA's Jet Propulsion Laboratory has clarified the "whys" of IR photography, pointing the way to "pushing" IR film to even better results and developing completely new approaches to imaging ( Bearman et al. 1993). ...
Article
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Tattoos can have cultural or medical significance. Occasionally, evidence of this type of body modification may be found in archaeological remains. This paper describes three tattoos found in a collection of human remains from the site of Semna South in Sudanese Nubia. The tattoos date to the Meroitic period, about 2000 years ago. Two tattoos were located on the dorsal surfaces of naturally mummified hands. These tattoos were examined using infra-red reflectography to enhance visibility. The tattoos are relatively complex designs and may relate to the social status or the group affiliation of the individuals bearing them.
Article
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Scholars using still cameras to take (mostly) oblique imagery from a low-flying aircraft of various possible archaeologically related anomalies can be defined as aerial archaeologists. At present, as well as in the past, aerial/air archaeology has been acquiring data almost exclusively in the visible range of the electromagnetic spectrum. This phenomenon can largely be attributed to the critical imaging process and sometimes unconvincing results related to the film-based approach of near-infrared (NIR) photography. To overcome the constraints of detecting and interpreting only the varying visible colors in vegetation (the so-called crop marks), while still maintaining the flexible and low-cost approach characteristic for aerial archaeology, a consumer digital still camera was modified to capture NIR radiation. By its spectral characterization, more insight was gained into its imaging properties and necessary guidelines for data processing, and future improvements could be formulated, all in an attempt to better capture the archaeologically induced anomalous growth stresses in crops.
Article
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IR camera systems can be used for reflectographic analyses to detect and visualize underdrawings in paintings. Five technologies have been compared: CCD Si, FPA InGaAs, FPA HgCdTe and InSb detectors, and a vidicon tube. The comparison has been performed studying the relative contrast measured on homogeneous pictorial layers in infrared regions between 800 and 5000 nm. This comparison was completed through measurements of spectral transmittance (400–2500 nm) made with a spectrometer. The results have been related to the kind of pigment and of medium and to the thickness of the layer. All the systems have been tested also on the field, on paintings belonging to different museums. Some results are discussed.
Book
Remote sensing of the environment is covered through spectroscopic analysis of soil and vegetation response during active and passive sensing. Fundamental aspects of spectroscopic methods for environmental applications are given. Applications range from remote sensing of saline soils, soil moisture detection, landscape evolution, weed detection, fluorescence imaging, and use of vegetation indices to measure ecosystem variables such as plant stress.
Article
This paper discusses the philosophical and technical aspects of remote sensing for vegetation damage assessment. Answers are presented for these questions: What constitutes remote sensing evidence of vegetation damage? How is vegetation damage interpreted from remotely sensed data? How can the damage be assessed? The answers to these questions are discussed in detail relevant to normal color and color-infrared aerial photography. Consideration is given to details of film reaction to variations in spectral reflectance patterns. Damages showing morphological or physiological changes are discussed relative to spectral reflectance changes and presented as a means to code damage types. An hypothesis for quantitatively monitoring forest damage is presented.
Book
Austin Richards takes readers on a visual tour of the electromagnetic spectrum beyond the range of human sight, using imaging technology as the means to 'see' invisible light. Dozens of colorful images and clear, concise descriptions make this an intriguing, accessible technical book. Richards explains the light spectrum, including visible light, and describes the advanced imaging technologies that enable humans to synthesize our own version of 'alien' vision at different wavelengths, with applications ranging from fire fighting and law enforcement to botany and medicine. © 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). All rights reserved.
Chapter
Remarkably similar results have been reported in a number of studies that evaluated patterns of change in leaf reflectance spectra within the 400–850 nm wavelength range that occur with plant physiological stress. A variety of stressors have been imposed on species ranging from grasses to conifers and deciduous trees. In all cases, the maximum difference between control and stressed states occurred as a reflectance increase near 700 nm. This common response near 700 nm, as well as correspondingly increased reflectance in the green-yellow spectrum, are explained by the tendency of stress to reduce leaf chlorophyll concentration and by the in vivo absorption properties of chlorophyll. To determine the extent to which stress-induced changes in the reflectance of stressed vegetation at the landscape scale may be similar to those observed commonly for individual leaves, a row crop of corn was exposed to various levels of N fertilization, and canopy reflectances were measured using AVIRIS imagery. Changes in corn canopy reflectance with N deficiency were spectrally similar to the commonly observed leaf reflectance responses to stress, with maximum reflectance differences between N-deficient and control plots at 730 nm. Only far-red reflectance increased significantly (P=0.05) with relatively mild N deficiency, but reflectance in the green and far-red spectra correlated equally well with field estimates of leaf chlorophyll and laboratory measurements of leaf N concentration. A complete lack of N fertilizer increased reflectance significantly in both the green and far-red spectra and decreased reflectance in the near-infrared. Additionally, short-term water stress caused changes in corn canopy reflectance that differed from the responses to N deficiency, altering reflectance substantially only in the near-infrared, where it increased by as much as 2.5 percent. Consequently, remote sensing may be used not only to detect plant stress in monoculture stands but also to predict its cause.
Article
The concept of quantum efficiency eta for a photodiode is introduced and a scheme is presented allowing the determination of eta as a function of the wavelength of the incident light and the structural parameters of the photodiode. The particular cases of field induced junctions and abrupt junctions are discussed in detail. using appropriate one-dimensional approximations.
Article
Multi-spectral imaging (MSI), which was developed to explore the surface of the earth and other planets from space, has been adapted to read and record faded or burnt manuscripts. The authors show how MSI achieved new readings from carbonised and damaged fragments of papyrus scrolls from Herculaneum, Petra and the Judean Desert. The method has potential for investigating the degraded ornamental surfaces of other artefacts.
Article
Infra-red reflectography, a method of improving the detect ability of underdrawings in medieval paintings, is discussed. It is shown that the results can be explained with the Kubelka-Munk analysis of the optical properties of paint films. Measurements are described providing a plot of the paint layer thickness required to hide an underdrawing, against the wavelength. Such curves show a maximum around λ = 2.0 microns. Infra-red to visible image translation systems are surveyed to illustrate the choice of an infra-red vidicon television system to obtain reflectograms. This system is responsive to radiation up to 1.9 microns. The interpretation of infra-red reflectograms is briefly discussed. Limitations of the method are indicated.
Article
Beach erosion at Cape Kialegak, St. Lawrence Island, Alaska, revealed the frozen, naturally mummified body of a 1600 year old Eskimo woman. The body has extensive tattooing on the dorsal aspects of both the right and left forearms, hands and fingers. The tattooing pattern corresponds with known design patterns for the Old Bering Sea phase.
Article
A reflectographic apparatus, equipped with an image processor, has been used to obtain a trichromatic image of paintings comprehensive of both visible and infrared (700–1000nm) regions. The first step has been to reproduce with MIPP (multispectral image processing of paintings) images similar to those obtained with IR Kodak colour film. A good discrimination of both pigments and overpainting is possible with this technique which operates in a more flexible and powerful way than IR ‘false colour’ photography. Results are shown relative to a test panel and a tempera painting with extensive overpaint. The possibility of utilizing this technique to correlate a single pigment with its MIPP image is now under investigation.
Article
Cet article décrit la technique photographique qui utilise le fait que certains éléments, trouvés dans les pigments colorants, émettront des radiations infrarouges quand ils seront irradiés par une source lumineuse bleu-vert. La terminologie utilisée y est tout d'abord définie, et la différence entre la fluorescence visible excitée par rayons ultraviolets et la luminescence infrarouge invisible excitée par une lumière bleu-vert y est expliquée. Y sont également exposées les méthodes utilisées pour obtenir l'illumination d'excitation bleu-vert pour la filtration nécessaire à l'appareil. Les illustrations établissent une comparaison entre les exemples d'écailles de peinture et de peintures, photographiés par la méthode ultraviolette bien connue et par celle de luminescence infrarouge. Les auteurs pensent que la luminescence infrarouge pourrait trouver des applications importantes dans l'examen de tableaux au vernis épais, qui sont difficiles à voir clairement et à photographier sous une lumière ultraviolette. D'autres possibilités y sont discutées, qui peuvent s'avérer de valeur dans l'étude des matériaux d'art.
Article
Photographic emulsions sensitized to wave-lengths of radiation in the infrared region of the spectrum have been used in technical studies for a number of years. During excavation of the Barbeau Creek Rock Shelter, in Randolph County, southern Illinois, in 1952 and 1953, I experimented with infrared films, taking pictures of profiles in the site. The midden in this shelter consisted largely of a light, dun-colored loess which came from the tops of the bluffs in the area. Ordinary photographs of the profiles in the midden are dull and without sufficient contrast between features to be useful for analytical purposes. The possibility of making dramatic, high contrast prints from infrared negatives is well known. For this reason photographs of the profiles were made with infrared film. The results the first season were promising. Not only did features in the profiles show up clearly on the prints, but some appeared which were not visible in prints made with panchromatic film and which were not apparent to the eye.
Article
Forensic photography, which was systematically established in the late 19th century by Alphonse Bertillon of France, has developed a lot for about 100 years. The development will be more accelerated with the development of high technologies, in particular the digital technology. This paper reviews three studies to answer the question: Can the SLR digital camera replace the traditional silver halide type ultraviolet photography and infrared photography? 1. Comparison of relative ultraviolet and infrared sensitivity of SLR digital camera to silver halide photography. 2. How much ultraviolet or infrared sensitivity is improved when removing the UV/IR cutoff filter built in the SLR digital camera? 3. Comparison of relative sensitivity of CCD and CMOS for ultraviolet and infrared. The test result showed that the SLR digital camera has a very low sensitivity for ultraviolet and infrared. The cause was found to be the UV/IR cutoff filter mounted in front of the image sensor. Removing the UV/IR cutoff filter significantly improved the sensitivity for ultraviolet and infrared. Particularly for infrared, the sensitivity of the SLR digital camera was better than that of the silver halide film. This shows the possibility of replacing the silver halide type ultraviolet photography and infrared photography with the SLR digital camera. Thus, the SLR digital camera seems to be useful for forensic photography, which deals with a lot of ultraviolet and infrared photographs.
Article
Image quality and sensitivity are important criteria when selecting a camera for machine vision. This paper describes how these quantities are defined and how they are measured. It is intended as a practical guide and the measurements can be done quite easily. Nevertheless, a thorough theoretical background is presented for the different tasks in keeping with the German engineer's saying "Es gibt nichts Praktischeres als eine gute Theorie" (there is nothing more practical than a good theory).
Article
In an attempt to extract information relevant for agriculture in remotely sensed wheat crops, MIVIS hyperspectral images are analyzed in the visible and near-infrared domains. Through the selection, by means of a principal component analysis (PCA), of two endmembers of wheat, related respectively to well-developed and stressed plants, a water deficiency is detected among the spectral population of wheat. The image is then modeled by a spectral mixture analysis (unmixing) of these two wheat endmembers, soil, and shade. Resulting fraction images are interpreted in terms of crop vitality (level of green biomass) in relation to stress presence and compared to field knowledge. In addition, these images allow mapping the leaf area index (LAI) over the whole scene, with an empirical relationship based on 12 ground measurements of this variable. This work shows the interest of the approach combining PCA and unmixing for stress detection and mapping of agronomic variables, with a good accuracy compared to spectral ratio analysis. It provides relevant support for crop monitoring and precision agriculture, by means of numerical cartographic products obtained by hyper- (super-) spectral remote sensing. It demonstrates the need for improved methodologies derived from hyperspectral data analysis, and reveals that, through such methods, one can, however, retrieve a significant amount of information with limited number of spectral channels (10–20), highlighting the potential of superspectral observations.
Article
The recognition of subsurface soil disturbances that have no surviving surface displacement often depends on an anomalous growth of the crop that overlies them. These disturbances are sometimes evidences of man's past activities. The very slight differentials of colour and height in growing crops are frequently difficult to record through a normal film and filter combination. In order to test the capacity of the multispectral technique, a four camera sensor was flown over archaeological sites in central southern England in the summer of 1970. Known sites were used in various geological settings, producing growth marks of differing characteristics. The sensor included the near infrared and this showed distinct advantages at the early stages of cereal growth. Des anomalies locales croissance dans une moisson permettent souvent de dPceler des anomalies sous-jacentes du sol non visibles d la surface, anomalies qui ont parfois une signification archkologique. Comme il est dificile d'enregistrer sur films normaux les IkgPres diffirences dans la couleiir et la hauteur qui apparaissent dans une moisson en croissance, on a essay une technique multispectrale avec un senseur a quatre camiras on a photo-graphii dans I'M 1970 des sites archkologiques au coeur du midi de I'Angle-terre. Les caractiristiques des anomalies de croissance dkpendent de I'environnement gkologique. L'emploi du proche infra-rouge est d'un avantage certain en dkbut de croissance des ckrkales. Die Aufdeckung unterirdischer Bodenstorungen, die sich nicht auf der Erdoberflache fortsetren, ist oft an dem anomalen Wachstum des Getreides erkennbar. Diese Storungen sind manchmal Zeugnis fur menschliche Aktivitaten in der Vergangenheit. Die sehr geringen Farb-und Wachstums-unterschiede sind haufig mit normalen Film-und Filterkombinationen schwierig zu registrieren. Umdie Leistungsfahigkeit der Multispektral-Technik zu testen, wurde im Sommer 1970 ein Flug mit einem rnit vier Kameras ausgeriisteten Sensor iiber archaologischen Standorten im zentralen Siidengland ausgefiihrt. Bekannte Platze unter verschiedenen geoiogischen Bedingungen wurden aufgenommen, so dass man Wachstumsmerkmale verschiedener Charakter-istika erhalt. Der Sensor erfasste auch den nahen Infrarot-Bereich, der deutliche Vorteile im fruhen Wachstumsstadium von Getreide zeigte.
Article
Current one-shot, handheld Digital Still Cameras (DSCs) generally offer different file formats to save the captured frames: Joint Photographic Experts Group (JPEG), RAW and/or Tag(ged) Image File Format (TIFF). Although the JPEG file format is the most commonly used file format worldwide, it is incapable of storing all original data, something that also occurs, to a certain extent, for large TIFF files. Therefore, most professional photographers prefer shooting RAW files, often described as the digital photography’s equivalent of a film negative. As a RAW file contains the absolute maximum amount of information and original data generated by the sensor, it is the only scientifically justifiable file format. In addition, its tremendous flexibility in both processing and postprocessing also makes it beneficial from a workflow and image quality point of view. On the other hand, large file sizes, the required software and proprietary file formats remain hurdles that are often too difficult to overcome for many photographers. Aerial photographers who shoot with handheld DSCs should be familiar with both RAW and other file formats, as their implications cannot be neglected. By outlining the complete process from photon capture to the generation of pixel values, additionally illustrated by real-world examples, the advantages and particularities of RAW aerial photography should become clear.
Book
This book designed as a text for a one-semester undergraduate course presents a nonmathematical treatment of optics. The material is divided into 11 chapters entitled: Early Ideas of Light, the Classical Theories, Modern Theories, Geometrical Optics, Polarization, Lasers, Holography, the Eye, Seeing, Light and Color in Nature, and Color Science. Additional mathematical details are included in the three appendixes. (BLM)
Article
The near infrared absorption spectrum of liquid water at 20°C has been reinvestigated using a PbS cell detector system. The total spectral range investigated was from 0.70 to 2.50µ. A curve is included which shows five prominent absorption bands at 0.76, 0.97, 1.19, 1.45, and 1.94µ;and a table gives experimental results of water absorption at 20°C.
Article
The paper describes how many types of inexpensive digital camera can be used to take monochrome and false colour infra-red photographs. The method avoids many of the limitations of infra-red sensitive film and produces excellent results rapidly and at low cost.
Article
Protocols for photography of archaeological textiles to detect components of differing chemistry that are indicative of colourants were developed. Parameters of light source, camera distance, filter type, film type, film speed, and aperture size were evaluated for visible, UV-reflectance, UV-fluorescence, and infrared photography. Using these techniques facilitates selective sampling for further analysis that maximizes critical data acquisition while minimizing destruction of the artefact. Hence, forensic photography of archaeological perishable materials should be regarded as a precursor to destructive analytical methods.
Conference Paper
In the two centuries of photography, there has been a wealth of invention and innovation aimed at capturing a realistic and pleasing full-color two-dimensional representation of a scene. In this paper, we look back at the historical milestones of color photography and bring into focus a fascinating parallelism between the evolution of chemical based color imaging starting over a century ago, and the evolution of electronic photography which continues today. The second part of our paper is dedicated to a technical discussion of the new Foveon X3 multi-layer color image sensor; what could be descried as a new more advanced species of camera sensor technology. The X3 technology is compared to other competing sensor technologies; we compare spectral sensitivities using one of many possible figures of merit. Finally we show and describe how, like the human visual system, the Foveon X3 sensor has an inherent luminance-chrominance behavior which results in higher image quality using fewer image pixels.
Conference Paper
For various reasons, aerial archaeologists use(d) film when studying their objects in the Near InfraRed (NIR). However, even the use of colour InfraRed (CIR) emulsions remained severely restricted till today due to some ignorance or a severe lack of knowledge about the subject and - not at least - the critical imaging process. This error-prone film-based workflow belongs now to the past, thanks to the advent of digital cameras. In this article, two new approaches will be outlined, both in an attempt to overcome the constraints on the common archaeological interpretation of varying visible colours in vegetation: the use of modified hand-held digital cameras to photograph the NIR spectrum on the one hand, as well as future plans to digitally capture both Red and NIR wavelengths simultaneously on the other. Besides additional technical background information on NIR photography, the paper treats the advantages (and disadvantages) of NIR to normal archaeological aerial imaging. In the end, an introduction of a new, remotely controlled system to support (aerial) archaeologists in their (NIR) photography is given together with several approaches to NIR image processing.
Article
The archaeological landscape is a fragile, disappearing and frequently little understood resource; conventional methods of field research tend to be both time-consuming and labour-intensive and produce a patchy and inconsistent record which reflects varying site visibility rather than poor research. If we are to preserve, or at least mitigate against damage to, this resource successfully, or even to undertake realistic assessment of landscapes as part of nationally established research agendas we need to re-assess our methods of site identification and discovery radically, lest the conservation movement lead to an entirely non-research based process of preservation or examination based on random discovery rather than academic selectivity. The Heslerton Parish Project was established in 1980 to provide a research framework for the rescue excavations then in progress at Cook's Quarry, West Heslerton (Powlesland 1981; Powlesland et al. 1986). The project research area covers a 10km square, centered upon West Heslerton, and spans a number of distinctive geomorphological zones which extend both to the east and west of the area and form a representative sample of the landscape at the interface of the Yorkshire Wolds and the Vale of Pickering In parallel with rescue excavations, a ten-year program of intensive oblique aerial photography (1978-1988) was undertaken with the assistance of a local farmer and pilot, Carl Wilkinson. By 1988 this survey had generated new evidence which radically changed our understanding of the landscape, particularly in the low-lying plain of the Vale of Pickering. By 1990 it was felt that the returns from additional oblique air-photography had reached saturation level, such that only changes in agricultural methods on a field-by-field basis were likely to generate a significant increase in returns. The present project has been made possible by the award of an Natural Environment Research Council (NERC) Data Award, a grant from English Heritage to cover data processing and interpretation and the support and assistance provided by the University of Durham and the North Yorkshire County Sites and Monuments Record (SMR).