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Review of drones, photogrammetry and emerging sensor technology for the study of dykes: Best practises and future potential

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... In some scientific disciplines, UAS use might be considered more developed than in volcanology, and several general and subject-specific reviews contain relevant insight for volcanological applications [e.g. Bhardwaj et al. 2016;Colomina and Molina 2014;Dering et al. 2019;Giordan et al. 2018;Nex and Remondino 2014;Turner et al. 2016;Villa et al. 2016;Zhang and Kovacs 2012]. Here, we build on a recent review of the use of small UAS in volcanic landscapes [Jordan 2019], to explore the wider application of UAS in volcanology, and detail the procedures involved. ...
... Extending such mapping over the whole crater would allow the detection of preferential orientations of magmatic intrusions and help decipher the complex history of the composite volcano. UAS-based imagery thus allows outcrop mapping at a level of spatial extent and detail that would not be possible using traditional field techniques [Dering et al. 2019], with structural information (e.g. dip magnitudes and orientations, and preferential alignments of faults, joints, dykes or strata) being extracted with increasingly automated methods from orthomosaics and DEMs [Dering et al. 2019]. ...
... UAS-based imagery thus allows outcrop mapping at a level of spatial extent and detail that would not be possible using traditional field techniques [Dering et al. 2019], with structural information (e.g. dip magnitudes and orientations, and preferential alignments of faults, joints, dykes or strata) being extracted with increasingly automated methods from orthomosaics and DEMs [Dering et al. 2019]. The widening use of SfMphotogrammetry is driving parallel advances in analysis tools for 3-D point clouds (e.g. ...
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Unoccupied aircraft systems (UAS) are developing into fundamental tools for tackling the grand challenges in volcanology; here, we review the systems used and their diverse applications. UAS can typically provide image and topographic data at two orders of magnitude better spatial resolution than space-based remote sensing, and close-range observations at temporal resolutions down to those of video frame rates. Responsive deployments facilitate dense time-series measurements, unique opportunities for geophysical surveys, sample collection from hostile environments such as volcanic plumes and crater lakes, and emergency deployment of ground-based sensors (and robots) into hazardous regions. UAS have already been used to support hazard management and decision-makers during eruptive crises. As technologies advance, increasing system capabilities, autonomy and availability, supported by more diverse and lighter-weight sensors, will offer unparalleled potential for hazard monitoring. UAS will provide opportunities for pivotal advances in our understanding of complex physical and chemical volcanic processes.
... Digital elevation models (DEMs) and the dissemination of geographical information systems have changed the way the terrain is characterized, analysed, monitored and modelled, especially since the 1990s. DEMs have been produced from dense collections of topographic points, manned aircraft photogrammetry, digitizing of topographic maps (Stevens et al., 1999), satellite remote sensing (Baldi et al., 2002;Kerle, 2002;Diefenbach et al., 2013), light detection and ranging (lidar; Mouginis-Mark and Garbeil, 2005;Mazzarini et al., 2007;Favalli et al., 2009;Fornaciai et al., 2010), and radar interferometry (InSAR; Rowland et al., 1999;Poland, 2014). The technological developments and decreasing cost of unmanned aerial vehicles (UAV), accompanied by the development of advanced photogrammetry algorithms involving image matching and structure from motion (SfM) and computing power, originated a significant methodological leap that greatly affected practices in Earth surface sciences (James et al., 2019). ...
... Several recent reviews have been produced showing the applicability of UAV-based topographical surveys in volcanological research. Dering et al. (2019) present a review on UAV-based photogrammetry for mapping dikes in very high resolution, emphasizing best practices. A recent summary about the use of small UAVs for collecting immediate and real-time aerial data in volcanic environments during and after an eruption is provided by Jordan (2019), highlighting the UAVs' advantages for mapping, sample collection, thermal imaging, magnetic surveys and slope stability studies and as platforms for carrying outgassing measurement sensors. ...
... commercial software based on automatic feature detection, image matching and modelling using SfM algorithms. Extensive methodological reviews on the application of UAV photogrammetry using this technique are found in Westoby et al. (2012), Smith et al. (2016) and Dering et al. (2019). The point cloud was processed using the full image scale; matching of image pairs was processed using the aerial grid/corridor model, and geometrically verified matching was processed using automatic advanced key point extraction. ...
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Fogo in the Cabo Verde archipelago off western Africa is one of the most prominent and active ocean island volcanoes on Earth, posing an important hazard both to local populations and at a regional level. The last eruption took place between 23 November 2014 and 8 February 2015 in the Chã das Caldeiras area at an elevation close to 1800 ma.s.l. The eruptive episode gave origin to extensive lava flows that almost fully destroyed the settlements of Bangaeira, Portela and Ilhéu de Losna. During December 2016 a survey of the Chã das Caldeiras area was conducted using a fixed-wing unmanned aerial vehicle (UAV) and real-time kinematic (RTK) global navigation satellite system (GNSS), with the objective of improving the terrain models and visible imagery derived from satellite platforms, from metric to decimetric resolution and accuracy. The main result is a very high resolution and quality 3D point cloud with a root mean square error of 0.08 m in X, 0.11 m in Y and 0.12 m in Z, which fully covers the most recent lava flows. The survey comprises an area of 23.9 km2 and used 2909 calibrated images with an average ground sampling distance of 7.2 cm. The dense point cloud, digital surface models and orthomosaics with 25 and 10 cm resolutions, a 50 cm spaced elevation contour shapefile, and a 3D texture mesh, as well as the full aerial survey dataset are provided. The delineation of the 2014/15 lava flows covers an area of 4.53 km2, which is smaller but more accurate than the previous estimates from 4.8 to 4.97 km2. The difference in the calculated area, when compared to previously reported values, is due to a more detailed mapping of the flow geometry and to the exclusion of the areas corresponding to kīpukas (outcrops surrounded by lava flows). Our study provides a very high resolution dataset of the areas affected by Fogo's latest eruption and is a case study supporting the advantageous use of UAV aerial photography surveys in disaster-prone areas. This dataset provides accurate baseline data for future eruptions, allowing for different applications in Earth system sciences, such as hydrology, ecology and spatial modelling, as well as to planning. The dataset is available for download at https://doi.org/10.5281/zenodo.4718520 (Vieira et al., 2021).
... In previous years, numerous articles have reviewed these technologies, covering topics such as LiDAR technology (Buckley et al., , 2008Hodgetts, 2013;Telling et al., 2017), digital photogrammetry (Westoby et al., 2012;Vollgger et al., 2019), and hyperspectral sensors (Asadzadeh et al., 2016), but none of them have reported the application of a methodology for a systematic review. ...
... However, more attention was given to works using LiDAR data in the study of reservoir analogues. The use of aerial and terrestrial photogrammetry has increased in remote-sensing studies (Westoby et al., 2012;Telling et al., 2017;Vollgger et al., 2019), and this is currently reflected in the study of reservoir analogues. ...
... DOM acquisition, assembly, and interpretation can be easily adapted to both incremental and disruptive innovations. Novel technologies such as UAVs (Colomina and Molina, 2014;Vollgger et al., 2019) and immersive virtual reality (iVR) (Gonzaga et al., 2018) are appearing in research applications and should soon be applied to daily usage. The interpretation and visualization of digital outcrops is still an individual activity. ...
Article
The study of outcrop analogues of petroleum reservoirs is well established in the petroleum industry through the use of digital outcrop models (DOMs). These models, which are also known as virtual outcrop models (VOMs) or 3D outcrops, are of great importance for understanding the behavior of actual reservoirs. This topic has been reviewed by many authors, and the studies vary in detail according to the technologies involved. The present study applies systematic review methodology traversing a number of articles to find the trends in studies utilizing DOMs. The articles included in this review indicate that the technologies used to generate DOMs are still predominantly classified as Light Detection and Ranging (LiDAR) and digital photogrammetry, with the first being present in most of the works, and the latter attracting attention owing to the popularity of unmanned aerial vehicles (UAVs). These studies have attracted a significant amount of attention to outcrop analysis, and the information acquired can be used to better fit reservoir simulations. Furthermore, a trend is identified with a focus on outcrop geometry and structural data. This work also discusses some of the available opportunities related to the generation of DOMs as well as emerging technologies that can improve the quality of the outcrop models in order to provide better reservoir simulations. Finally, this work discusses the findings and highlights of the articles answering the initially raised research questions.
... UAVs are commonly used in active, dormant, and extinct volcanic settings in order to map volcanic deposits (e.g., Dering et al., 2019;Thiele et al., 2017;Gomez and Kennedy, 2018;Carr et al., 2019;Jordan, 2019;Smith et al., 2019). For reviews in using UAVs to survey volcanic settings see Dering et al. (2019) and Jordan (2019). ...
... UAVs are commonly used in active, dormant, and extinct volcanic settings in order to map volcanic deposits (e.g., Dering et al., 2019;Thiele et al., 2017;Gomez and Kennedy, 2018;Carr et al., 2019;Jordan, 2019;Smith et al., 2019). For reviews in using UAVs to survey volcanic settings see Dering et al. (2019) and Jordan (2019). In addition, UAVs are also widely used for structural (e.g., Vasuki et al., 2014;Bemis et al., 2014;Vollgger and Cruden, 2016) and stratigraphic studies (e.g., Nieminski and Graham, 2017;Chesley et al., 2017;Nesbit et al., 2018) in all tectonic settings. ...
... For a list of other photogrammetry software, including open source-options, see (https://en.wikipedia.org/wiki/Comparison_ of_photogrammetry_software), or discussions in Dering et al. (2019) and Bemis et al. (2014). In Agisoft Metashape, vertical orthomosaics are generated using a user defined projection with two axes. ...
Article
Volcaniclastic stratigraphy can be difficult to map and describe due to its complex nature. However, such stratigraphy preserves information about fluctuations in volcanic activity and sedimentation and is vital to understanding volcanic systems. Uncrewed aerial vehicle (UAV) based analysis of volcanic stratigraphy can enhance mapping and analysis, especially on vertical surfaces where outcrop exposure is greatest. Here we present a method for using small UAVs to produce vertical grain size and bedding measurement logs, or quantitative stratigraphic columns, of vertical volcaniclastic stratigraphy. We demonstrate the range of high-accuracy measurements and parameters that can be collected for building measurement logs using consumer grade UAVs through a case study in the Marysvale volcanic field where we collected 34,422 grain measurements from 21 individual units. The purpose of producing such measurement logs is to enhance lithofacies analysis through the use of large quantitative datasets and improve the reproducibility of data reporting. Whereas descriptions of volcaniclastic units such as those describing grading are often reported qualitatively, we describe methods for calculating numerical parameters for enhanced lithologic analysis including grain size, grading, clast to matrix ratios, and shape characteristics. The methods described in this paper can enhance field data acquisition, mapping, and quantitative analysis of volcaniclastic deposits and are applicable to a wide range of other geologic settings where coarse-grained clastic sedimentary deposits exist.
... The fracture characterization in analog outcrops is usually carried out in situ. However, remote sensing techniques powered by LiDAR (Light Detection And Ranging) [6], [7] and/ or Unmanned Aerial Vehicles (UAV) image acquisitions, combined digital photogrammetry algorithms like the Structure from Motion (SfM) and Multi-view Stereo (MSV) [8]- [10], can be used to create digital representations of the outcrop such as orthorectified images and digital outcrop models (DOM) that enable geoscientists to perform fracture characterization in a virtual environment [5], [8], [11], [12]. The UAV-SFM-MVS photogrammetry processing is a low-cost method for outcrop geometry reconstruction. ...
... The fracture characterization in analog outcrops is usually carried out in situ. However, remote sensing techniques powered by LiDAR (Light Detection And Ranging) [6], [7] and/ or Unmanned Aerial Vehicles (UAV) image acquisitions, combined digital photogrammetry algorithms like the Structure from Motion (SfM) and Multi-view Stereo (MSV) [8]- [10], can be used to create digital representations of the outcrop such as orthorectified images and digital outcrop models (DOM) that enable geoscientists to perform fracture characterization in a virtual environment [5], [8], [11], [12]. The UAV-SFM-MVS photogrammetry processing is a low-cost method for outcrop geometry reconstruction. ...
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The identification of fractures and discontinuities has great importance on the fluid flow estimation in hydrocarbon reservoirs since they influence the properties of porosity and permeability. Due to the inaccessibility and sparsity of reservoir data, the fracture characterization is generally assessed through the study of outcrop analogues using remote sensing or in situ observations by a specialist. Considering the remote sensing methods, the unmanned Aerial Vehicle (UAV) acquisition combined with Structure from Motion (SfM) photogrammetry is a low-cost way to generate products like orthorectified images, allowing manual and automated methods of fracture trace detection. Automatic approaches, commonly used to address this problem, present some known limitations and disadvantages due to the nature of the outcrops and weather conditions during UAV acquisitions. In this work, we focus on fracture detection over karstic regions that are highly fractured. For this, we evaluated a series of adaptive segmentation methods based on thresholding. The Sauvola local adaptive segmentation presented the best result when compared to a manually annotated ground truth. The segmentation results were further improved by the use of the binary denoising method Non-Local means. We also carried an evaluation of the influence of the sun position in the fracture detection, and to reduce this inherent bias we combined three UAV acquisitions done over the karstic carbonate outcrop, namely Rosário pavement in the Jandaíra formation northeast Brazil. With the proposed methodology we acquired more accurate fracture data over the study area, which follows the directional statistics of previous works carried out in the region. INDEX TERMS Discrete fracture network, fracture detection, discontinuity tracing, outcrop analogue.
... UASs are especially useful for structural assessments, allowing the study of the appearance, formation, geomorphology and dynamics of volcano craters and crater lakes at unprecedented resolution [18,23,24,31,34]. The quality of UAS-derived photogrammetric products [23] offers the possibility of low cost and repeated overflights and monitoring at volcanic craters even during eruptive activity [35], identification of structures, fissures and faults [5,36] and the measurement of structures and fall deposits at craters [37]. Therefore, at Ebeko volcano, we gathered such photogrammetric data in an attempt to better understand eruption sites and the locations of fluid escape. ...
... The active crater chain of Ebeko (Figure 1d,f) hosts three main craters referred to as the South Crater, Middle Crater and North Crater, with temporally varying cold and hot lakes indicative of a shallow groundwater level and interaction with the geothermal system [46]. Relatively strong eruptions of the Vulcanian type occur episodically, with an activity that appears to migrate along the NNE-SSW Vernadsky Ridge, such as eruptions in 1934- 35,1965, 2011 and 2016-2017 that occurred from the Middle Crater and in 1967-1971, 1987-1991, 2009-2010, 2016-20 from the North Crater and a deep funnel on its northeastern rim [41,47,48]. Sometimes eruptions have even occurred simultaneously at different craters. ...
Article
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Vulcanian explosions are hazardous and are often spontaneous and direct observations are therefore challenging. Ebeko is an active volcano on Paramushir Island, northern Kuril Islands, showing characteristic Vulcanian-type activity. In 2019, we started a comprehensive survey using a combination of field station records and repeated unoccupied aircraft system (UAS) surveys to describe the geomorphological features of the edifice and its evolution during ongoing activity. Seismic data revealed the activity of the volcano and were complemented by monitoring cameras, showing a mean explosion interval of 34 min. Digital terrain data generated from UAS quadcopter photographs allowed for the identification of the dimensions of the craters, a structural architecture and the tephra deposition at cm-scale resolution. The UAS was equipped with a thermal camera, which in combination with the terrain data, allowed it to identify fumaroles, volcano-tectonic structures and vents and generate a catalog of 282 thermal spots. The data provide details on a nested crater complex, aligned NNE-SSW, erupting on the northern rim of the former North Crater. Our catalog of thermal spots also follows a similar alignment on the edifice-scale and is also affected by topography on a local scale. This paper provides rare observations at Ebeko volcano and shows details on its Vulcanian eruption style, highlighting the relevance of structural and morphologic control for the geometry of craters and tephra fallout as well as for structurally controlled geothermal activity.
... Since flight altitude is often limited by terrain restraints, pilot safety, and the safety of inhabitants of the survey area, it takes delicate work to optimize the sample frequency and flight line spacing in order to achieve the spatial resolution sought for the survey [10]. Small UASs allow for a reduction in above-ground flight level, slow and stable flight velocities, and close line spacing [11]. However, UASs have a much slower speed and shorter flight time, which limits the survey area that can be covered. ...
... This will require flight lines, spacing, and flight speed to be pre-set if specific resolution requirements are to be made. Setting the speed of the UAS and flight lines before conducting the survey can produce magnetic maps of with a resolution set to exact specifications [11]. With these improvements in instrument design, more thorough testing of the magnetic gradiometer can be conducted for high-resolution magnetic mapping. ...
Article
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The use of unmanned aircraft systems (UASs) for geophysical exploration and environmental monitoring allows for flexible, quick, and effective surveys with high-resolution results. Developing and integrating a magnetic gradiometer with a UAS allows for geophysical exploration of magnetic subsurface features such as geologic structures, metal detection, or locating unexploded ordinances (UXOs). This paper presents the development of a magnetic gradiometer for integration with a UAS. The magnetic gradiometer is composed of two fluxgate magnetometers, two GPS receivers, and a microcontroller-based controlling and data-logging system. The components of the magnetic gradiometer system are lightweight and inexpensive, ideal for use with a UAS. Initial field tests for the magnetic gradiometer are discussed. The initial results demonstrate the magnetic gradiometer’s data coherency along with future improvements that will improve the design of the instrument.
... In addition to classical field surveys (e.g., [20,21]), volcanic areas have been studied by highresolution, remotely captured images, Orthomosaics and Digital Surface Models (DSMs), especially using unmanned aerial systems (UASs), also known as drone or Unmanned Aerial Vehicles (UAVs), which have high resolution imaging capabilities and an ability to map steep to vertical slopes (e.g., [22][23][24][25][26][27]). Following the drone survey, UAV-captured images are combined with Structure from Motion (SfM) photogrammetry techniques [28][29][30][31] to derive the ortho-mosaic imagery and digital surface model. ...
... In addition to classical field surveys (e.g., [20,21]), volcanic areas have been studied by high-resolution, remotely captured images, Orthomosaics and Digital Surface Models (DSMs), especially using unmanned aerial systems (UASs), also known as drone or Unmanned Aerial Vehicles (UAVs), which have high resolution imaging capabilities and an ability to map steep to vertical slopes (e.g., [22][23][24][25][26][27]). Following the drone survey, UAV-captured images are combined with Structure from Motion (SfM) photogrammetry techniques [28][29][30][31] to derive the ortho-mosaic imagery and digital surface model. ...
Article
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In the present work we highlight the effectiveness of integrating different techniques and tools for better surveying, mapping and collecting data in volcanic areas. We use an Immersive Virtual Reality (IVR) approach for data collection, integrated with Geographic Information System (GIS) analysis in a well-known volcanological site in Santorini (Metaxa mine), a site where volcanic processes influenced the island’s industrial development, especially with regard to pumice mining. Specifically, we have focused on: (i) three-dimensional (3D) high-resolution IVR scenario building, based on Structure from Motion photogrammetry (SfM) modeling; (ii) subsequent geological survey, mapping and data collection using IVR; (iii) data analysis, e.g., calculation of extracted volumes, as well as production of new maps in a GIS environment using input data directly from the IVR survey; and finally, (iv) presentation of new outcomes that highlight the importance of the Metaxa Mine as a key geological and volcanological geosite.
... The required hardware for this initial stage of the workflow is readily available and includes consumer-grade cameras and personal computers, as well as unmanned aerial vehicle (UAV) in the case of aerial image acquisition. Indeed, the ease of deployment and low cost of the aforementioned tools is largely responsible for the rapid proliferation of SfM-MVS-based close-range remote sensing within the earth and environmental sciences over the past decade [5][6][7][8][9][10][11][12][13]. Model registration seeks to rectify the model's location and attitude within a local or global reference frame, which is achieved via a series of geometric transformations (scaling, translation, and rotation: i.e., the similarity transform [14]). ...
Article
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Geotagged smartphone photos can be employed to build digital terrain models using structure from motion-multiview stereo (SfM-MVS) photogrammetry. Accelerometer, magnetometer, and gyroscope sensors integrated within consumer-grade smartphones can be used to record the orientation of images, which can be combined with location information provided by inbuilt global navigation satellite system (GNSS) sensors to geo-register the SfM-MVS model. The accuracy of these sensors is, however, highly variable. In this work, we use a 200 m-wide natural rocky cliff as a test case to evaluate the impact of consumer-grade smartphone GNSS sensor accuracy on the registration of SfM-MVS models. We built a high-resolution 3D model of the cliff, using an unmanned aerial vehicle (UAV) for image acquisition and ground control points (GCPs) located using a differential GNSS survey for georeferencing. This 3D model provides the benchmark against which terrestrial SfM-MVS photogrammetry models, built using smartphone images and registered using built-in accelerometer/gyroscope and GNSS sensors, are compared. Results show that satisfactory post-processing registrations of the smartphone models can be attained, requiring: (1) wide acquisition areas (scaling with GNSS error) and (2) the progressive removal of misaligned images, via an iterative process of model building and error estimation.
... Although UAVs have significantly increased their capacity to collect data in the field with higher density (Dering et al., 2019), it has been pointed out that the use of additional tools improves the precision of the results (Jimenez et al., 2017). ...
Article
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Today, topography is an essential part for the construction of civil works in Mexico and in the world, obtaining it has become a complicated task due to the large areas to be built, the difficult access that puts the integrity of individuals at risk; and the high requirement of personnel for the tasks. Currently, photogrammetry using unmanned aerial vehicles (UAV) has been potentiated due to the infinity of uses, autonomy and little demand for resources, to carry out tasks in short times. Furthermore, the topography was, until some years ago, quasi-static, however due to the alteration generated by human activities it has been transformed into a dynamic activity. This work presents the procedures to carry out a topographic survey in the Querétaro valley, in an area called "El Ensueño", it has had a subsidence fault for years, and has been in constant movement, causing considerable damage to infrastructure. The present study reveals for the first time an orthomosaic and a Digital Elevation Model (DEM) of the study site, for a survey with UAV it is necessary to use Ground Control Points (GCP), in order to correct the DEM by orthorectification of the images obtained during the flight by means of UAV. The results obtained show a total error in centimeters of 3.33 and image pixels in 0.311, both in the X, Y and Z space, which represent an acceptable error considering that the latter must be less than 0.6 pixels, so therefore, the alignment of the images and measurement by GPS were performed correctly during the processing. Furthermore, the Digital Terrain Model allows to observe a steep difference between one extreme and the other, which will make it location of the fault that defines the subsidence zone (affected area). Resumen Hoy en día, la topografía forma parte indispensable para la construcción de obras civiles en México y en el mundo, su obtención se ha vuelto una tarea complicada debido a las grandes áreas para levantar, el difícil acceso que pone en riesgo la integridad de los in-dividuos y el alto requerimiento de personal para las tareas. En la actualidad, la fotogrametría mediante vehículos aéreos no tripula-dos (VANT) se ha potencializado debido a la infinidad de usos, autonomía y poca demanda de recursos para llevar a cabo labores en tiempos cortos. Además la topografía era, hasta hace algunos años cuasiestática, sin embargo, el ritmo acelerado de las actividades humanas la han convertido en dinámica. En este trabajo se presenta el procedimiento utilizado para realizar un levantamiento topo-gráfico en el valle de Querétaro, en una zona denominada "El Ensueño", esta presenta una falla por subsidencia desde hace años y ha estado en continuo movimiento, provocando cuantiosos daños en la infraestructura. El presente estudio da a conocer por prime-ra vez un ortomosaico y un Modelo Digital de Elevación (MDE) del sitio en estudio. Para un levantamiento con VANT es necesario usar Puntos de Control Terrestre (PCT) con la finalidad de corregir el MDE mediante la ortorectificación de las imágenes obtenidas durante el vuelo, por medio de VANT. Los resultados obtenidos, muestran un error total en centímetros de 3.33 y de imagen en pi-xeles de 0.311, ambos en el espacio X, Y y Z, los cuales representan un error aceptable, considerando que este último debe ser inferior a 0.6 pixeles, por lo tanto, la alineación de las imágenes y medición mediante GPS fueron realizadas de forma correcta durante el procesamiento. Además, el Modelo Digital del Terreno (MDT) muestra una muy marcada diferencia entre uno y otro lado de la falla, lo que puede indicar que esta es una herramienta muy útil para identificar las áreas afectadas por la subsidencia con un método rápido y más preciso. Descriptores: Vehículo aéreo no tripulado, subsidencia, ortomosaico, modelo digital de elevaciones, fotogrametría, monitoreo, Agisoft Meta Shape IngenIería InvestIgacIón y tecnología, volumen XXII (número 1), enero-marzo 2021: 1-12 ISSN 2594-0732 FI-UNAM 2 On the measure Of land subsidence thrOughOut dem and OrthOmOsaics using gPs and uaV https://doi.
... Photogrammetric techniques, too, can be successfully applied to study volcanic and geothermal hazards. The applications of these techniques range from change analyses in the morphology and structures of lava domes [17][18][19][20][21] and dykes [22] to volcanic landform monitoring [23], ancient lava flow field surveys [24], volcano-tectonic surveys [25], geothermal research [26,27], and volcanic gas and plumes [28][29][30][31]. These studies can additionally include the use of optical and thermal imaging capabilities [32] to provide frequent and detailed detection and monitoring while simultaneously permitting geoscientists to detect changes in volcanic activity without putting themselves in hazardous conditions. ...
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The utility of new imaging technologies to better understand hazardous geological environments cannot be overstated. The combined use of unmanned aerial vehicles (UAV) and digital photogrammetry (DP) represents a rapidly evolving technique that permits geoscientists to obtain detailed spatial data. This can aid in rapid mapping and analyses of dynamic processes that are modifying contemporary landscapes, particularly through the creation of a time series of digital data to help monitor the geomorphological evolution of volcanic structures. Our study comprises a short-term (in geological terms) monitoring program of the dynamic and diffuse Pisciarelli degas-sing structure caused by the interplay between intensive rainfall and hydrothermal activity. This area, an unstable fumarole field located several hundred meters east of the Solfatara Crater of the Campi Flegrei caldera (southern Italy), is characterized by consistent soil degassing, fluid emission from ephemeral vents, and hot mud pools. This degassing activity is episodically accompanied by seismic swarms and macroscopic morphology changes such as the appearance of vigorously degas-sing vents, collapsing landslides, and bubbling mud. In late-2019 and 2020, we performed repeated photogrammetric UAV surveys using the Structure from Motion (SfM) technique. This approach allowed us to create dense 3D point clouds and digital orthophotos spanning one year of surveys. The results highlight the benefits of photogrammetry data using UAV for the accurate remote monitoring and mapping of active volcanoes and craters in harsh and dangerous environments.
... For this purpose it is necessary to acquire surface elevation points that subsequently are processed to build Digital Elevation Models (DEMs). The main techniques of acquisition are: i) the traditional digitalization of contour lines and height points from available cartographic maps (Tarquini et al. 2007); ii) Aerial Stereo Photogrammetry (Gwinner et al. 2006); iii) Satellite Stereo Photogrammetry (Beyer et al. 2018); iv) Airborne Laser Scanning and v) the most recent Drone technology (Dering et al. 2019). ...
Chapter
The eruptive history of a volcano can be investigated by analyzing the changes of its topography through time. This type of analysis can be a useful support to improve studies aimed at volcanic hazard assessment for very densely populated active or quiescent volcanic zones as the Somma-Vesuvio (SV) area. For the first time, in this work the morphological evolution of the SV volcanic edifice from 1876 to nowadays is presented through the reconstruction of topographies obtained from IGM (Italian Geographic Military Institute) historical maps (1876, 1906 and 1929) and remote sensing techniques (e.g. LiDAR). In detail, the multi-temporal morphological analysis has been focused on the Gran Cono area. The main working environment has been the ESRI platform (ArcGIS 10®), but other specific software have been involved to manage the geo-referencing procedures and conversion data (TN-Sharc, IGM-Traspunto/Cartlab). Morphological analyses and volume changes quantification related to the summit portion of the SV edifice from 1876 to nowadays are presented. The morphometric analyses were obtained by using height profiles along the four main direction (N-S, W-E, NW-SE and NE-SW), the changes in volume were estimated elaborating each Digital Elevation Model (DEM) in the area of interest.
... Remote or dangerous volcanic areas have been classically studied by aerial or satellite remotely sensed images, which have several limitations: (1) high-resolution data are very expensive to cover large-scale geological objects and the resolution can be poor for some targets, (2) it can be challenging to plan a specific survey by an airplane, due to high costs or remoteness of the site, (3) it is impossible to map steep to vertical slopes by images acquired in vertical nadir and (4) images are mostly 2D. Recently, unoccupied aerial systems (UASs), due to their high imaging capabilities, have been used to study volcanic eruption sites (Müller et al. 2017), dykes (Dering et al. 2019), volcano-tectonic relations (Walter et al. 2018;Bonali et al. 2019) and active faults in volcanic areas (Rust and Whitworth 2019), as well as faults and landslides in non-volcanic environment (Rathje and Franke 2016;Gao et al. 2017). UASs are also known as drones, aerial photography systems and unmanned aerial vehicles. ...
Article
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Direct outcrop observation and field data collection are key techniques in research, teaching and outreach activities in volcanic areas. However, very often outcrops are of difficult or impossible access, such as in areas with active volcanoes or steep cliffs. Classical remote-sensing surveys by satellites or airplanes are expensive, rarely reach sufficient resolution to allow high-quality 3D visualisation of volcanic features and do not facilitate mapping of vertical cliffs. We describe a novel approach that uses immersive Virtual Reality (VR) based on real-world 3D Digital Outcrop Models (DOMs) from images surveyed by “unoccupied aerial system” (UAS). 3D DOMs are built up using the Structure-from-Motion (SfM) photogrammetry technique, and a VR scene is created using game engine technologies. Immersive real-time exploration of the environment is possible through a head-mounted display, e.g. Oculus Rift. Tools embedded in the VR environment allow the user to map polygons, lines and point features. Tools also allow to measure orientation, dip, inclination, azimuth, area and thickness and even take virtual photographs. Using three examples of volcanic areas with different geological features, we demonstrate the potential of our approach to allow users to be able to virtually map and measure remotely, and to collect data for research and teaching. Our approach is of paramount importance also for outreach, as it allows non-specialist audiences (e.g. common citizens) to experience and appreciate highly complex volcanic features through customised, hands-on immersive VR tools.
... Opportunities for rapid and cost-effective collection of very high-resolution airborne hyperspectral data are beginning to be realised through new technologies such as drones with shortwave infrared (SWIR) hyperspectral sensors (e.g. Dering et al., 2019). Data across the visible-near infrared (VNIR) part of the spectrum collected from these platforms have been shown to have advantages across a number of research areas including acid mine drainage monitoring and outcrop mapping (e.g. ...
Article
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Key alteration minerals associated with epithermal and porphyry Cu–Au mineralisation have been successfully identified using HyMap airborne hyperspectral imagery in a regolith-dominated terrain in the southern Gawler Ranges, South Australia. Alteration assemblages were mapped using Spectral Feature Fitting, a spectral matching algorithm, identifying the spatial distribution of localised advanced argillic and broader argillic alteration. X-ray diffraction (XRD) analysis was undertaken to independently identify the mineralogy of 57 surface soil and rock samples collected from the study area. This analysis confirmed the presence of key alteration minerals including alunite, pyrophyllite and dickite. The integration of spectral and XRD analytical techniques allowed interpretation of mineralogical patterns across the landscape. This study demonstrates that it is possible to identify surface alteration related to potential mineralisation using airborne hyperspectral imagery and semi-quantitative XRD even in a weathered regolith-dominated terrain. • KEY POINTS • Advanced argillic and argillic alteration identified through hyperspectral image analysis in a regolith-dominated terrain • X-ray diffraction used to validate the presence of advanced argillic alteration minerals alunite, pyrophyllite and dickite in the landscape • Relationship of advanced argillic and argillic alteration interpreted in two key landscape features in the context of a porphyry mineral system • Demonstrates potential for detection of alteration signatures with airborne hyperspectral imagery in regolith-dominated terrains elsewhere
... The integration of spectral and geophysical UAS-based information offers a refined scale between airborne and ground surveys. Numerous studies and reviews have investigated the potential of UASs for various applications, e.g., in the fields of agriculture and forestry, structural geology, and sedimentology [1][2][3][4][5][6][7]. ...
Article
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Mapping geological outcrops is a crucial part of mineral exploration, mine planning and ore extraction. With the advent of unmanned aerial systems (UASs) for rapid spatial and spectral mapping, opportunities arise in fields where traditional ground-based approaches are established and trusted, but fail to cover sufficient area or compromise personal safety. Multi-sensor UAS are a technology that change geoscientific research, but they are still not routinely used for geological mapping in exploration and mining due to lack of trust in their added value and missing expertise and guidance in the selection and combination of drones and sensors. To address these limitations and highlight the potential of using UAS in exploration settings, we present an UAS multi-sensor mapping approach based on the integration of drone-borne photography, multi- and hyperspectral imaging and magnetics. Data are processed with conventional methods as well as innovative machine learning algorithms and validated by geological field mapping, yielding a comprehensive and geologically interpretable product. As a case study, we chose the northern extension of the Siilinjärvi apatite mine in Finland, in a brownfield exploration setting with plenty of ground truth data available and a survey area that is partly covered by vegetation. We conducted rapid UAS surveys from which we created a multi-layered data set to investigate properties of the ore-bearing carbonatite-glimmerite body. Our resulting geologic map discriminates between the principal lithologic units and distinguishes ore-bearing from waste rocks. Structural orientations and lithological units are deduced based on high-resolution, hyperspectral image-enhanced point clouds. UAS-based magnetic data allow an insight into their subsurface geometry through modeling based on magnetic interpretation. We validate our results via ground survey including rock specimen sampling, geochemical and mineralogical analysis and spectroscopic point measurements. We are convinced that the presented non-invasive, data-driven mapping approach can complement traditional workflows in mineral exploration as a flexible tool. Mapping products based on UAS data increase efficiency and maximize safety of the resource extraction process, and reduce expenses and incidental wastes.
... Structure from motion (SFM) is currently widely used and has shown great potential in the field of high-efficiency and lowcost 3D reconstructions (Dering et al., 2019;Barrile et al., 2022). SFM is a technique for estimating 3D structures in a sequence of multiple two-dimensional images containing visual motion information. ...
Article
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The cliff ecosystem is one of the least human-disturbed ecosystems in nature, and its inaccessible and often extreme habitats are home to many ancient and unique plant species. Because of the harshness of cliff habitats, their high elevation, steepness of slopes, and inaccessibility to humans, surveying cliffs is incredibly challenging. Comprehensive and systematic information on cliff vegetation cover is not unavailable but obtaining such information on these cliffs is fundamentally important and of high priority for environmentalists. Traditional coverage survey methods—such as large-area normalized difference vegetation index (NDVI) statistics and small-area quadratic sampling surveys—are not suitable for cliffs that are close to vertical. This paper presents a semi-automatic systematic investigation and a three-dimensional reconstruction of karst cliffs for vegetation cover evaluation. High-resolution imagery with structure from motion (SFM) was captured by a smart unmanned aerial vehicle (UAV). Using approximately 13,000 records retrieved from high-resolution images of 16 cliffs in the karst region Guilin, China, 16 models of cliffs were reconstructed. The results show that this optimized UAV photogrammetry method greatly improves modeling efficiency and the vegetation cover from the bottom to the top of cliffs is high-low-high, and very few cliffs have high-low cover at the top. This study highlights the unique vegetation cover of karst cliffs, which warrants further research on the use of SFM to retrieve cliff vegetation cover at large and global scales.
... Imagery was collected using a DJI Phantom 4 Pro and its integrated camera (20-megapixel CMOS sensor) along horizontal flight lines ~ 30-60 m from the cliff faces using horizontal and ~ 30 degree downward oriented viewing angles and vertical and horizontal overlaps of ~ 80%. These image sets were then reconstructed using a structure-from-motion multi-view-stereo (SfM-MVS) workflow 30,43 to create a database of 3-D digital outcrop point cloud models at ground sampling distances of ~ 2-5 cm. Specific details of each of the surveys is included in the Supplementary Method and the dataset can be downloaded from https ://doi.org/10.26180 ...
Article
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The feedback between dyke and sill intrusions and the evolution of stresses within volcanic systems is poorly understood, despite its importance for magma transport and volcano instability. Long-lived ocean island volcanoes are crosscut by thousands of dykes, which must be accommodated through a combination of flank slip and visco-elastic deformation. Flank slip is dominant in some volcanoes (e.g., Kilauea), but how intrusions are accommodated in other volcanic systems remains unknown. Here we apply digital mapping techniques to collect > 400,000 orientation and aperture measurements from 519 sheet intrusions within Volcán Taburiente (La Palma, Canary Islands, Spain) and investigate their emplacement and accommodation. We show that vertically ascending dykes were deflected to propagate laterally as they approached the surface of the volcano, forming a radial dyke swarm, and propose a visco-elastic model for their accommodation. Our model reproduces the measured dyke-aperture distribution and predicts that stress accumulates within densely intruded regions of the volcano, blocking subsequent dykes and causing eruptive activity to migrate. These results have significant implications for the organisation of magma transport within volcanic edifices, and the evolution and stability of long-lived volcanic systems.
... Paisiriyuenyong [35] provided a brief explanation of how to use UAVs at each stage of mine development, and Ren et al. [36] reviewed case studies on the use of UAVs for mine operations, such as terrain surveying and 3-D modeling, land damage assessment, ecological environment monitoring, and pollution monitoring. Buczyńska [37] reviewed a few cases where UAVs were used in the reclamation phase, and Dering et al. [38] conducted a review of the UAV-based structure from motion (SfM) methodology that can be applied to the mapping and analysis of dykes and their host rocks. However, no systematic review has been performed on the applications of UAVs in mining by classifying the entire mining process into the three phases of exploration, exploitation, and reclamation. ...
Article
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Over the past decade, unmanned aerial vehicles (UAVs) have been used in the mining industry for various applications from mineral exploration to mine reclamation. This study aims to review academic papers on the applications of UAVs in mining by classifying the mining process into three phases: exploration, exploitation, and reclamation. Systematic reviews were performed to summarize the results of 65 articles (June 2010 to May 2020) and outline the research trend for applying UAVs in mining. This study found that UAVs are used at mining sites for geological and structural analysis via remote sensing, aerial geophysical survey, topographic surveying, rock slope analysis, working environment analysis, underground surveying, and monitoring of soil, water, ecological restoration, and ground subsidence. This study contributes to the classification of current UAV applications during the mining process as well as the identification of prevalent UAV types, data acquired by sensors, scales of targeted areas, and styles of flying control for the applications of UAVs in mining.
... It will also be greatly conditioned by the sensitivity and weight of the sensor(s) that should be mounted, and that depends on the volcanic issues to be addressed (e.g., measurements of surface, internal and atmospheric phenomena) (Gonzalez Toro and Tsourdos 2018). Amongst these problems, it is fundamental to map and characterize active volcanic structures on the surface, such as lava flows (De Beni et al. 2019), intrusions (Dering et al. 2019), volcano-tectonics features and deformation (Bonali et al. 2019). Repeated UAV measurements over time enable quantification of the temporal evolution of these structures (Derrien et al. 2015;Darmawan et al. 2018). ...
Article
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This article presents a review of the use of Unmanned Aerial Vehicles (UAVs) in the context of geohazards. The pluri-disciplinary role of drones is outlined in numerous studies associated with mass movements, volcanology, flooding events and earthquakes. Scientific advances and innovations of several research teams around the world are presented from pre-events investigations to crisis management. More particularly, we emphasize the actual status of technology, methodologies and different applications that have emerged with the use of UAVs for each domain. It is shown that the deployment of drones in geohazards context has experienced a tremendous increase during the last 10 years, with the development of more and more miniaturized, flexible and reliable systems. The use of such technology (UAV platform, instrumentation, methodologies) is different for each domain, depending on the spatial extension and the time scale of the observed phenomenon, but also on the practical constraints associated to the civil aviation agencies regulations (outside or within urban areas, before or during a crisis…). This paper also highlights the use of recent methodologies associated with semi-automatic/automatic segmentation or deep learning for the processing of important amounts of data provided by UAVs. Finally, although still sparse, the joint use of UAVs and satellite data is progressing and remains a challenge for future studies in the context of geohazards.
... In geological applications, thermal data can be used for the identification of landforms, lithologies and structural features. Optical and TLS sensors are widely used to map and monitor slope instabilities, and can be used in co-registration with data from other sensors, such as thermal sensors, to enhance the slope characterization [94,[141][142][143]. Methodologies that incorporate objectbased image analysis (OBIA) with two machine learning (ML) methods, namely the multilayer perceptron neural network (MLP-NN) and random forest (RF), have been developed for landslide detection [144]. ...
Article
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Coastal retreat is a non-recoverable phenomenon that—together with a relevant proneness to landslides—has economic, social and environmental impacts. Quantitative data on geological and geomorphologic features of such areas can help to predict and quantify the phenomena and to propose mitigation measures to reduce their impact. Coastal areas are often inaccessible for sampling and in situ surveys, in particular where steeply sloping cliffs are present. Uses and capability of infrared thermography (IRT) were reviewed, highlighting its suitability in geological and landslides hazard applications. Thanks to the high resolution of the cameras on the market, unmanned aerial vehicle-based IRT allows to acquire large amounts of data from inaccessible steep cliffs. Coupled structure-from-motion photogrammetry and coregistration of data can improve accuracy of IRT data. According to the strengths recognized in the reviewed literature, a three-step methodological approach to produce IRTs was proposed.
... Although being a feasible alternative for most case scenarios, photogrammetry of inaccessible or extensive regions may increase the costs and complexity of the task, restricting the available areas of study [23]. Also, when it comes to airspace control regulations worldwide, the most accessible in terms of flight permission for UAVs is at low altitude. ...
Article
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This paper proposes a technique named Printgrammetry, a structured workflow that allows the extraction of 3D models from Google Earth platform through the combination of image captures from the screen monitor with Structure from Motion algorithms. This technique was develop to help geologists and other geoscientists in acquiring 3D photo-realistic models of outcrops and natural landscapes of big proportions without the need of field mapping and expensive equipment. The methodology is detailed aiming to permit easy reproducibility and focused on achieving the highest resolution possible by working with the best images that the platform can provide. The results have shown that it is possible to obtain visually high quality models from natural landscapes from Google Earth by acquiring images at high Level of Detail regions of the software, using a 4K monitor, multi-directional screenshots and by marking homogeneously spaced targets for georeferencing and scaling. The geometric quality assessment performed using Light Detection and Ranging ground truth data as comparison shows that the Printgrammetry dense point clouds have reached 98.1\% of the total covered area under 5 meters of distance for the Half Dome case study and 96.7\% for the Raplee Ridge case study. The generated 3D models were then visualized and interacted through an immersive virtual reality software that allowed geologists to manipulate this virtual field environment in different scales. This technique is considered by the authors to have a promising potential for research, industrial and educational projects that doesn't requires highly precision models.
... To gain access to the steep and unstable exposures within Caldera Taburiente, images collected via unmanned aerial vehicle (UAV) were used to construct three-dimensional (3-D) digital outcrop models using a structure-from-motion multiview-stereo photogrammetric workflow (SfM-MvS; cf. Bemis et al., 2014;Dering et al., 2019). These digital outcrop models and details of the methods used to construct them are described in (Thiele et al., 2019a;Thiele et al., 2020). ...
Preprint
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Field observations and unmanned aerial vehicle surveys from Caldera Taburiente (La Palma, Canary Islands, Spain) show that pre-existing dykes can capture and re-direct younger ones to form multiple dyke composites. Chill margins suggest that the older dykes were solidified and cooled when this occurred. In one multiple dyke example, an 40Ar/39Ar age difference of 200 kyr was determined between co-located dykes. Petrography and geomechanical measurements (ultrasonic pulse and Brazilian disc tests) show that a microscopic preferred alignment of plagioclase laths and sheet-like structures formed by non-randomly distributed vesicles give the solidified dykes anisotropic elastic moduli and fracture toughness. We hypothesise that this anisotropy led to the development of margin-parallel joints within the dykes, during subsequent volcanic loading. Finite element models also suggest that the elastic contrast between solidified dykes and their host rock elevated and re-oriented the stresses that governed subsequent dyke propagation. Thus, the margin- parallel joints, combined with local concentration and rotation of stresses, favoured the deflection of subsequent magma- filled fractures by up to 60° to form the multiple dykes. At the edifice scale, the capture and deflection of active intrusions by older ones could change the organisation of volcanic magma plumbing systems and cause unexpected propagation paths relative to the regional stress. We suggest that reactivation of older dykes by this mechanism gives the volcanic edifice a structural memory of past stress states, potentially encouraging the re-use of older vents and deflecting intrusions along volcanic rift zones or towards shallow magma reservoirs.
... To gain access to the steep and unstable exposures within Caldera Taburiente, images collected via unmanned aerial vehicle (UAV) were used to construct three-dimensional (3-D) digital outcrop models using a structure-from-motion multi-view-stereo photogrammetric workflow (SfM-MvS; cf. Bemis et al., 2014;Dering et al., 2019). These digital outcrop models and details of the methods used to construct them are described in . ...
Article
Full-text available
Field observations and unmanned aerial vehicle surveys from Caldera Taburiente (La Palma, Canary Islands, Spain) show that pre-existing dykes can capture and re-direct younger ones to form multiple dyke composites. Chill margins suggest that the older dykes were solidified and cooled when this occurred. In one multiple dyke example, an 40Ar/39Ar age difference of 200 kyr was determined between co-located dykes. Petrography and geomechanical measurements (ultrasonic pulse and Brazilian disc tests) show that a microscopic preferred alignment of plagioclase laths and sheet-like structures formed by non-randomly distributed vesicles give the solidified dykes anisotropic elastic moduli and fracture toughness. We hypothesize that this anisotropy led to the development of margin-parallel joints within the dykes, during subsequent volcanic loading. Finite element models also suggest that the elastic contrast between solidified dykes and their host rock elevated and re-oriented the stresses that governed subsequent dyke propagation. Thus, the margin-parallel joints, combined with local concentration and rotation of stresses, favored the deflection of subsequent magma-filled fractures by up to 60° to form the multiple dykes. At the edifice scale, the capture and deflection of active intrusions by older ones could change the organization of volcanic magma plumbing systems and cause unexpected propagation paths relative to the regional stress. We suggest that reactivation of older dykes by this mechanism gives the volcanic edifice a structural memory of past stress states, potentially encouraging the re-use of older vents and deflecting intrusions along volcanic rift zones or toward shallow magma reservoirs.
... • planning for an appropriate GSD (e.g., 1-3 cm is generally sufficient for most fine scale applications), • understanding the relationship between focal length, sensor size and flight altitude on the expected GSD, • understanding the importance of photograph quality and target type on the outcome of the SfM workflow (e.g., the white water rapids at Corredeira do Suplício cannot be reconstructed), • utilizing a flight planning application and flight controller software to ensure proper front and side overlap between photographs • understanding the impact of file type and compression of the photographs on the SfM products Across the various commercial and open source software available for the SfM processing, a plethora of studies (e.g., [108][109][110][111][112][113][114][115]) have compared the impact of software choice, software settings, photograph pre-processing, etc., for both above and below water applications. The SfM products and datasets derived from them may become the only digital reference data to sites that are permanently modified, in this case, the rheophile habitats that no longer exist after inundation (Figures 14c and 15). ...
... However, few studies focus on smaller dikes. According to Dering et al. (2019), at a lower scale, terrestrial SfM is more suitable than UAV photogrammetry. For instance, it is more convenient with less field constraints such as wind conditions. ...
Article
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Nature based solutions are growing rapidly in order to mitigate in the near future the effects of climate change and rise of sea level on most anthropogenic coasts. In that frame, the CHERbourg bLOC (CHERLOC) project aims to study new coastal engineering solutions (overtopping, sediment transport) thanks to two new artificial units in two test sites (Normandy, France) considering biodiversity preservation but also societal acceptability. This study details an efficient method to monitor such coastal infrastructure using terrestrial Structure from Motion (SfM). In 2021, surveys were conducted to acquire pictures in April, May, June and November. A time series of 3D photogrammetric models was generated using open source SfM software. The first model was georeferenced using Ground Control Points (GCP) measured by Differential Global Navigation Satellite System (DGNSS) so that it could be used as a reference for the following point clouds using surrounding ripraps assumed to be non-mobile through the period of the study. The georeferencing Root Mean Square Error (RMSE) was found to be 1.8 cm for the April model whereas RMSEs of relative registrations of the following dates were found to be sub-centimetric. These results can be used to observe and measure blocks displacements as well as sand volumes evolution throughout the time series. The biggest displacement was found to be 23 cm between April and June. Sand topographic variation shows a continuous accumulation on selected cross-sections between April and November with an overall height accumulation of about 30 cm. Sand volumes measurements show consistent results with an added volume of 3.67 m3 on the previous areas.
... The quality of a 3D model mainly depends on the survey's quality and the photogrammetric reconstruction process. The survey's quality, in terms of accuracy, is dependent on various parameters: method, performances of UAS avionics, quality of cameras, the accuracy of GNSS observations [32], camera calibration [33][34][35] and the georeferencing method [36]. ...
Article
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Comparing photogrammetric performances of four user-grade unmanned aircraft systems (UAS) is the main aim of this paper. This study investigates what is the more suitable UAS for specific applications considering the required scale factor, such as for architectural, environmental and restoration purposes. Some photogrammetric surveys were conducted in a 5 ha area using a Phantom 4 Adv, Mavic 2 Pro, Mavic Air 2 and Mavic Mini 2. These unmanned aircrafts are commercial systems used mainly by private professionals. Some photogrammetric reconstructions were carried out by varying flight altitude and camera settings of the 4 UAS. Structure-from-motion (SfM) algorithms were applied to the images taken from the UASs. The surveys’ quality was analyzed by comparing the ground targets’ coordinates measured on the field with indirect georeferencing through global navigation satellite system (GNSS). Fifty targets were installed and arranged following a kind of regular grid. For each photogrammetric flight, the boundary conditions were maintained the same, as well as the flight trajectories and the ground control point distribution. Altimetric and planimetric residuals were reported and compared for each photogrammetric survey. Using a regular grid of ground targets, the result obtained from Phantom 4 is one order of magnitude better than the ones obtained from the other UASs. Mavic Mini 2 leads to an error average of about 5 cm. Remembering that the Mavic Mini 2 is an ultralight drone (it does not require a pilot’s license), it could significantly reduce costs compared to all the others.
... The use of DOMs for geological interpretation purposes has already been applied to several geological focus, ranging from analysis of the geometry of DOMs [6] to the analysis of structures and dykes [7], and others. Thus, able to demonstrate the wide capacity of interpretive assistance for the geologist, regarding the interpretation of rocky outcrops. ...
Conference Paper
The study of outcrops is one of the main ways of carrying out research in geology, because it offers direct analysis on the behavior of rocks. Thus, the study of analogous outcrops has been used by the oil industry, as they can be associated with other data and offer a more effective analysis in geological modeling of reservoir rocks. With the advancement of technology in recent years, the use of virtual environments has been gaining more space in geosciences, as they allow the user to analyse areas that are difficult to access and allow structural and geometric analysis of real-scale outcrops. Even though the use of Digital Outcrop Models (DOM) is becoming popular, the industry still suffers from a lack of software appropriate to interpret digital outcrops. In this paper we assess the performance of DOM to classify Lithofacies on out-crop of carbonate rocks in northeastern Brazil by using Mosis XP tools. Mosis XP is a software developed by Vizlab-X-Reality and GeoInformatics Lab specifically to perform DOM analysis and interpretation. Results confirm that texture and color attributes were satisfatory preserved in the virtual representation. Also, interpretation tasks were promising since allowed correctly identification of at least four distinct facies over the outcrop profile.
... Uncrewed aerial vehicles (UAVs) have revolutionised geological mapping by facilitating detailed and quantitative outcrop characterisation. Recent reviews highlight a variety of applications, including geotechnical investigations, geohazard assessment, structural analysis, stratigraphic mapping and teaching [1][2][3][4]. Most of these studies relied on an interpretation of outcrop colour captured using conventional lightweight RGB cameras, and geometric information from light detection and ranging (LiDAR) or structure from motion multi-view stereo (SfM-MVS) workflows [5]. ...
Article
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While uncrewed aerial vehicles are routinely used as platforms for hyperspectral sensors, their application is mostly confined to nadir imaging orientations. Oblique hyperspectral imaging has been impeded by the absence of robust registration and correction protocols, which are essential to extract accurate information. These corrections are especially important for detecting the typically small spectral features produced by minerals, and for infrared data acquired using pushbroom sensors. The complex movements of unstable platforms (such as UAVs) require rigorous geometric and radiometric corrections, especially in the rugged terrain often encountered for geological applications. In this contribution we propose a novel correction methodology, and associated toolbox, dedicated to the accurate production of hyperspectral data acquired by UAVs, without any restriction concerning view angles or target geometry. We make these codes freely available to the community, and thus hope to trigger an increasing usage of hyperspectral data in Earth sciences, and demonstrate them with the production of, to our knowledge, the first fully corrected oblique SWIR drone-survey. This covers a vertical cliff in the Dolomites (Italy), and allowed us to distinguish distinct calcitic and dolomitic carbonate units, map the qualitative abundance of clay/mica minerals, and thus characterise seismic scale facies architecture.
... The SfM digital photogrammetry technique allows precise 3D object models to be created from multiple unmanned aerial vehicle (UAV) stereo images. The 3D models generated by SfM photogrammetry are efficient for multi-scale analysis which is not comparable with traditional methods [6]. Recent developments in UAV and SfM techniques have made them a feasible option in many different applications [7]. ...
Article
Unmanned Aerial Vehicles (UAVs) have been used for accurate orthophoto generation based on advanced Global Navigation Satellite System (GNSS) techniques. In recent years, the UAV systems have become an effective tool for fast monitoring of damages caused by disasters such as the earthquake hazards. The conventional orthophoto generation based on ground control points takes too much time during emergency situations. In the study, different methodologies for the processing of the acquired GNSS Positioning data for direct georeferencing of UAVs were investigated in terms of various orbit products. Evaluating the fitness for emergency response applications, the ground control points (GCPs) also used for validation of the generated orthophoto without using GCPs and based on Precise Point Positioning (PPP) approach. In this study, Ultra-Rapid, Rapid and Final PPP methods based on GNSS observations were used for direct geo-referencing. Thirteen GCPs were located at the study area for the validation of the orthophoto accuracy generated by direct geo-referencing.
... Such missions can be performed by single or a swarm of drones. Captured images can then be stitched together, creating a 2D or 3D mosaic map [20]. Pre-disaster aerial images can be captured from satellite, manned flights, and by UAVs. ...
Article
The roles played by Unmanned Aerial Vehicles (UAVs) or drones in various military and commercial applications testify their necessity in today’s world. Recent advances in wireless communication technology, electronics, hardware & software, and other supporting technologies have led drone technology to a maturity level that it can be trusted with civil application domains such as disaster management. Time is of critical essence in disaster scenarios. Drones can speed up processes in various disaster management phases by providing an alternative platform with aerial support and a level of autonomy over traditional approaches. UAVs can perform pre-programmed missions of the affected regions, landscape mappings, and infrastructural analysis. Due to its multivariate applicability, current research shows a propensity towards the development & enhancement of current drone capabilities to augment their roles in disaster management. This paper identifies major overlapping areas in disaster management phases where drone technology can be effectually utilized. Drones are of multiple types with respective features and limitations. Information about different types of drones with their respective capabilities and limitations is also provided. To quantify disaster impacts, a mathematical model is provided. Finally, an illustration of a self-developed drone prototype development project targeted towards surveys and search & rescue missions, along with the importance of “Hardware in the Loop (HIL)” simulation analysis reports are presented.
... They greatly improve the characterization of outcrop geometry and structure, allowing accurate mapping of, e.g., fractures (e.g., [4], [5]), faults (e.g., [2]), lithology (e.g., [6]), sedimentary architecture, and (for some minerals) mineralogy (e.g., [7], [8]). These datasets, thus, have widespread applications in geohazard management, geotechnical engineering, oil and gas, and the minerals industry [1], [9], [10]. ...
Article
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The widespread application of drones and associated miniaturization of imaging sensors has led to an explosion of remote sensing applications with very high spatial and spectral resolutions. The 3-D ultrahigh-resolution digital outcrop models created using drones and oblique imagery from ground-based sensors are now commonly used in the academic and industrial sectors, while the generation of spatially accurate models has been greatly facilitated by the development of computer vision tools, such as structure from motion, and the correction of spectral attributes to achieve material reflectance measurements remains challenging. Following the development of a topographical correction toolbox (mephysto), we now propose a series of new tools that can leverage the detailed geometry captured by digital outcrop models to correct for illumination effects caused by oblique viewing angles and the interaction of light with complex 3-D surfaces. This open-source code is integrated into hylite, a python toolbox for the full 3-D processing and fusion of digital outcrop models with hyperspectral imaging data. We validate the performance of our novel method using a case study at an open-pit mine in Tharsis, Spain, and demonstrate the importance of accurate illumination corrections for quantitative spectral analyses. Significantly, we show that commonly applied spectral analysis techniques can yield erroneous results for data corrected using current state-of-the-art approaches. Our proposed method ameliorates many of the issues with these established approaches.
... UAV photogrammetry has been implemented for 3D stratigraphic and structural mapping in a variety of geological settings, including siliclastic (Nieminski and Graham, 2017;Chesley et al., 2017;Nesbit et al., 2018;Clark et al., 2018;Priddy et al., 2019;Pitts et al., 2020;Yeste, 2020;Durkin et al., 2020), carbonate (Corradetti et al., 2015;Madjid et al., 2018;Triantafyllou et al., 2019;Thomas et al., 2021;Vimpere et al., 2022;Menegoni et al., 2022), volcanic (Dering et al., 2019;Bonali et al., 2019), and mixed sedimentary environments (Zahm et al., 2016;Claussmann et al., 2021). This paper is concerned with 3D stratigraphic mapping of the fluvial-deltaic formations of the Pliocene-age Upper Productive Series at Yasamal Valley, Apsheron Peninsula, Azerbaijan (Fig. 1). ...
Article
Developments in digital outcrop geology have facilitated the stratigraphic, structural, and sedimentologic characterization of outcrop analogs for applications in the petroleum industry. Here, unmanned aerial vehicles (UAVs) and Structure from Motion photogrammetry have been used to create a digital outcrop model of the Upper Productive Series clastic succession in Yasamal Valley, Apsheron Peninsula, that serves as a valuable analog to hydrocarbon-rich Pliocene reservoirs of the South Caspian Basin. The UAVs provided an advantageous perspective on the low-gradient exposures along the depositional strike and allowed stratigraphic mapping in a 0.1 km² area, which was previously difficult to image in the field using conventional methods. Petrographic and mineralogical analyses of outcrop samples were also used to identify facies types. Key stratigraphic surfaces and depositional elements within the channelized succession were mapped with the aid of surface attributes to produce a high-resolution facies architecture and evaluate reservoir heterogeneity of the low to intermediate net-to-gross Balakhany Formation. The interpreted framework shows a range of reservoir types deposited in a prograding delta front setting, represented by an increase in sandstone-body proportions and degree of channelization within a coarsening-upward succession. Channel-body dimensions were measured and categorized based on published global datasets. Sandstone proportions were quantified, and rapid lateral and vertical variations in net-to-gross were revealed. This study provides useful information for correlation of wells and modeling of heterogeneous, low to moderate net-to-gross reservoirs of the offshore fields in the South Caspian Basin.
... For instance, in industrial accidents high temperatures and explosions pose a threat to UAS balance, stability, and control which affect ability to provide reliable information due to image deformation [49]. When UAS are used in higher altitudes lift is reduced and that affect flight autonomy [50]. ...
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... Photogrammetry is a technique that combines photogrammetry and computer vision algorithms to extract 3D geometries from a series of digital 2D images (Dering et al., 2019). Photogrammetry integrated with BIM can be used to monitor reinforced concrete column pouring (Omar et al., 2018) and excavation operations productivity (B€ ugler et al., 2017). ...
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Mineral exploration in the West Greenland flood basalt province is attractive because of its resemblance to the magmatic sulfide-rich deposit in the Russian Norilsk region, but it is challenged by rugged topography and partly poor exposure for relevant geologic formations. On northern Disko Island, previous exploration efforts have identified rare native iron occurrences and a high potential for Ni–Cu–Co–PGE–Au mineralization. However, Quaternary landslide activity has obliterated rock exposure in many places at lower elevations. To augment prospecting field work under these challenging conditions, we acquire high-resolution magnetic and multispectral remote sensing data using drones in the Qullissat area. From the data, we generate a detailed 3D model of a mineralized basalt unit, belonging to the Asuk Member of the Palaeocene Vaigat Formation. Different types of legacy data and newly acquired geo- and petrophysical as well as geochemical-mineralogical measurements form the basis of an integrated geological interpretation of the unoccupied aerial system (UAS) surveys. In this context, magnetic data aim to define the location and the shape of the buried magmatic body, and to estimate if its magnetic properties are indicative for mineralization. UAS-based multispectral orthomosaics are used to identify surficial iron staining, which serves as a proxy for outcropping sulfide mineralization. In addition, UAS-based digital surface models are created for geomorphological characterization of the landscape to accurately reveal landslide features. UAS-based magnetic data suggest that the targeted magmatic unit is characterized by a pattern of distinct positive and negative magnetic anomalies. We apply a 3D magnetization vector inversion (MVI) model to the UAS-based magnetic data to estimate the magnetic properties and shape of the magmatic body. By means of introducing constraints in the inversion, (1) UAS-based multispectral data and legacy drill cores are used to assign significant magnetic properties to areas that are associated with the mineralized Asuk Member, and (2) the Earth's magnetic and the palaeomagnetic field directions are used to evaluate the general magnetization direction in the magmatic units. Our results suggest that the geometry of the mineralized target can be estimated as a horizontal sheet of constant thickness, and that the magnetization of the unit has a strong remanent component formed during a period of Earth's magnetic field reversal. The magnetization values obtained in the MVI are in a similar range to the measured ones from a drillcore intersecting the targeted unit. Both the magnetics and topography confirm that parts of the target unit were displaced by landslides. We identified several fully detached and presumably rotated blocks in the obtained model. The model highlights magnetic anomalies that correspond to zones of mineralization and is used to identify outcrops for sampling. Our study demonstrates the potential and efficiency of using high-resolution UAS-based multi-sensor data to constrain the geometry of partially exposed geological units and assist exploration targeting in difficult or poorly exposed terrain.
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Structure-from-motion (SfM) photogrammetry has become an important tool for quantitative characterisation of outcrops. Digital outcrop models (DOMs) allow for the mapping of stratigraphy and discontinuous structures like folds, faults and fractures from cm to km scale and provide solutions that are difficult to constrain through subsurface data alone. With pristine, treeless exposures, the outcropping strata in Svalbard, Arctic Norway, hold exceptional potential for analogue studies and are ideally suited for the acquisition of high-resolution DOMs. We here present the acquisition, processing and integration of the Konusdalen West digital model data set, comprising both DOM and derived digital terrain model (DTM) data. Dronebased image acquisition took place over two weeks in July and August 2020. Fifteen differential GNSS control points were used to georeference and quality assure the model, five of which functioning as reference checkpoints. SfM processing of 5512 acquired images resulted in high-confidence, cm-scale resolution point clouds, textured mesh (DOM), tiled model, orthomosaics, and a DTM. The confidence-filtered dense cloud features a median inter-point distance of 1.57 cm and has an average point density of 3824.9 points m-2. For the five checkpoints, the dense cloud features root mean square errors of 2.0 cm in X, 1.3 cm in Y, 5.2 cm in Z, and 5.7 cm in XYZ. Drops in point confidence and point density are mainly found in areas with reduced image densities, and on the backside of boulders. Increased confidences and densities are present along the western flank of the Konusdalen West outcrop, where a fault-fracture network in mudstone-dominated stata is best exposed and photographed most extensively. The Konusdalen West DOM and DTM cover a 0.12 km2 area and span a 170 m elevation difference. The mean of the altitude of the checkpoints versus elevation of the dense cloud-derived DTM differed by less than a cm. The dense cloud-derived DTM closely matches an existing lower-resolution reference DTM of the area. The DOM covers the upper two-third of the mudstonedominated Late Jurassic-Early Cretaceous Agardhfjellet Formation. The Agardhfjellet Formation and its time-equivalents are regional cap rocks for CO2 sequestration and petroleum accumulations both on the offshore Barents Shelf and onshore Svalbard. Faults, formation members and established marker beds can be traced in the high-resolution model and have been used for the stratigraphic integration. Additional structural measurements and observations were taken in June 2021 to place the data in the geological context. Top and side-view orthomosaics feature maximum resolutions of 8 mm per pixel, enabling the mapping of fractures and other sub-cm features. The Konusdalen West digital model data set, together with the extensive drill cores through the same section near Longyearbyen, forms an ideal starting point for the generation of high-resolution, outcrop-truthed geomodels that are suitable for numerical modelling of fluid flow and appraisal of the regionally important caprock. Data described in this manuscript can be accessed at Norstore under https://doi.org/10.11582/2022.00027 (Betlem, 2022b).
Chapter
This chapter turns towards a specific type of hillslopes: volcanoes and how pointclouds can be used in volcanic geomorphology. The chapter first presents general features of volcanic geomorphology, before presenting the use of SfM-MVS and LiDAR to deal with the specific difficulties of working in volcanic environment (i.e. recording steep craters’ slopes or staying away from an erupting vent …). This chapter also uses this opportunity to present how pointcloud technologies can be used for micro-geomorphology (in the present case, from the example of a pyroclastic flow deposit surface differential erosion) as well as micro-geomorphology in the laboratory (in the example given, a small sand volcanoes). From the examples, the chapter also proposes a short discussion of the role of grid cell size and sampling strategy from a volcanic geomorphology dataset processed in R.
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This paper presents an optimization of the medication delivery drone with the Internet of Things (IoT)-Guidance Landing System based on direction and intensity of light. The IoT-GLS was incorporated into the system to assist the drone’s operator or autonomous system to select the best landing angles for landing. The landing selection was based on the direction and intensity of the light. The medication delivery drone system was developed using an Arduino Uno microcontroller board, ESP32 DevKitC V4 board, multiple sensors, and IoT mobile apps to optimize face detection. This system can detect and compare real-time light intensity from all directions. The results showed that the IoT-GLS has improved the distance of detection by 192% in a dark environment and exhibited an improvement in face detection distance up to 147 cm in a room with low light intensity. Furthermore, a significant correlation was found between face recognition’s detection distance, light source direction, light intensity, and light color (p < 0.05). The findings of an optimal efficiency of facial recognition for medication delivery was achieved due to the ability of the IoT-GLS to select the best angle of landing based on the light direction and intensity.
Thesis
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Digital photogrammetry is becoming an important tool for remote data acquisition. The use of digital outcrop models (DOMs) for fracture analysis has grown in the field of geosciences. Structure-from-Motion- Multi-view Stereo (SfM-MVS) is a recent technique that allows the creation of DOMs in a simple and inexpensive way. To direct an in-depth study of the application of SfM-MVS in the investigation of fractured media, the thesis sought to answer which parameters related to these systems can be obtained through the 3D models generated by SfM-MVS, and which factors have an influence on the data accuracy. Models of different outcrops (igneous, sedimentary and metamorphic rocks) were generated using sets of images at different scales, captured by different cameras and platforms. The models were analyzed using three approaches: to measure fracture properties; qualitative analysis of the factors that influence its quality and the derived data; and investigation of the quality levels offered by Agisoft Metashape. As a result, a list of best practices for fieldwork for the construction of an DOM was produced. It was concluded that the RPA is the most flexible platform available for different topographies, as it allows flight planning or manual piloting, while offering a good cost-benefit. In fracture analysis, algorithms that calculate orientation, spacing and persistence are easily implemented. These three parameters depend on the ability to identify fractures in the generated 3D model. This, in turn, is influenced by the spatial resolution and the presence of deformations in the model. For roughness, the difficulty of quantification lies in the efficient conversion of the Joint Roughness Coefficient (JRC) to three-dimensional space. In investigating the options offered by the Metashape program, the analyzed data suggest the accuracy-quality pairs high-high and highest-high as the best costbenefit ones, the first being the safest for application in field conditions. The results obtained point to the existence of a tripod, composed of three highly correlated elements: scope, time and cost. Changing one of them without impacting the others will sacrifice the final quality of the model, and consequently of the analysis. Another important result was the development of the multiplatform application SurvAid, an image survey planning tool; and the open software CAPI, dedicated to the structural analysis of DOMs. In conclusion, SfM-MVS proved to be a powerful technique for generating MDAs, which can be used in fracture analysis. Still, it should be seen as a complementary tool to field work.
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The feedback between dyke and sill intrusions and the evolution of stresses within volcanic systems is poorly understood, despite its importance for magma transport and volcano instability. Long-lived ocean island volcanoes are crosscut by thousands of dykes, which must be accommodated through a combination of flank slip and visco-elastic deformation. Flank slip is dominant in some volcanoes (e.g., Kilauea), but how intrusions are accommodated in other volcanic systems remains unknown. Here we apply digital mapping techniques to collect >400,000 orientation and aperture measurements from 519 sheet intrusions within Volcán Taburiente (La Palma, Canary Islands, Spain) and investigate their emplacement and accommodation. We show that vertically ascending dykes were deflected to propagate laterally as they approached the surface of the volcano, forming a radial dyke swarm, and propose a visco-elastic model for their accommodation. Our model reproduces the measured dyke-aperture distribution and predicts that stress accumulates within densely intruded regions of the volcano, blocking subsequent dykes and causing eruptive activity to migrate. These results have significant implications for the organisation of magma transport within volcanic edifices, and the evolution and stability of long-lived volcanic systems.
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Enhanced digital outcrop models attributed with hyperspectral reflectance data, or hyperclouds, provide a flexible, three-dimensional medium for data-driven mapping of geological exposures, mine faces or cliffs. This approach allows the collection of spatially contiguous information on exposed mineralogy and so provides key information for understanding mineralising processes, interpreting 1-D drillhole data, and optimising mineral extraction. In this contribution we present an open-source python workflow, hylite, for creating hyperclouds by seamlessly fusing geometric information with data from a variety of hyperspectral imaging sensors and applying necessary atmospheric and illumination corrections. These rich datasets can be analysed using a variety of techniques, including minimum wavelength mapping and spectral indices to accurately map geological objects from a distance. Reference spectra from spectral libraries, ground or laboratory measurements can also be included to derive supervised classifications using machine learning techniques. We demonstrate the potential of the hypercloud approach by integrating hyperspectral data from laboratory, tripod and unmanned aerial vehicle acquisitions to automatically map relevant lithologies and alterations associated with volcanic hosted massive sulphide (VHMS) mineralisation in the Corta Atalaya open-pit, Spain. These analyses allow quantitative and objective mineral mapping at the outcrop and open-pit scale, facilitating quantitative research and smart-mining approaches. Our results highlight the seamless sensor integration made possible with hylite and the power of data-driven mapping approaches applied to hyperclouds. Significantly, we also show that random forests (RF) trained only on laboratory data from labelled hand-samples can be used to map outcrop scale data.
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Mineral exploration in the West Greenland flood basalt province is attractive because of its resemblance to the magmatic sulphide-rich deposit in the Russian Norilsk region, but it is challenged by rugged topography and partly poor exposure for relevant geologic formations. On northern Disko Island, previous exploration efforts have identified rare native iron occurrences and a high potential for Ni-Cu-Co-PGE-Au mineralization. However, Quaternary landslide activity has obliterated rock exposure at many places at lower elevations. To augment prospecting field work under these challenging conditions, we acquire high-resolution magnetic and optical remote sensing data using drones in the Qullissat area. From the data, we generate a detailed 3D model of a mineralized basalt unit, belonging to the Asuk Member (Mb) of the Palaeocene Vaigat formation. A wide range of legacy data and newly acquired geo- and petrophysical, as well as geochemical-mineralogical measurements form the basis of an integrated geological interpretation of the unoccupied aerial system (UAS) surveys. In this context, magnetic data aims to define the location and the shape of the buried magmatic body, and to estimate if its magnetic properties are indicative for mineralization. High-resolution UAS-based multispectral orthomosaics are used to identify surficial iron staining, which serve as a proxy for outcropping sulphide mineralization. In addition, high-resolution UAS-based digital surface models are created for geomorphological characterisation of the landscape to accurately reveal landslide features. UAS-based magnetic data suggests that the targeted magmatic unit is characterized by a pattern of distinct positive and negative magnetic anomalies. We apply a 3D magnetization vector inversion model (MVI) on the UAS-based magnetic data to estimate the magnetic properties and shape of the magmatic body. By means of using constraints in the inversion, (1) optical UAS-based data and legacy drill cores are used to assign significant magnetic properties to areas that are associated with the mineralized Asuk Mb, and (2) the Earth’s magnetic and the paleomagnetic field directions are used to evaluate the general magnetization direction in the magmatic units. Our results indicate that the geometry of the mineralized target can be estimated as a horizontal sheet of constant thickness, and that the magnetization of the unit has a strong remanent component formed during a period of Earth’s magnetic field reversal. The magnetization values obtained in the MVI are in a similar range as the measured ones from a drillcore intersecting the targeted unit. Both the magnetics and topography confirm that parts of the target unit were displaced by landslides. We identified several fully detached and presumably rotated blocks in the obtained model. The model highlights magnetic anomalies that correspond to zones of mineralization and is used to identify outcrops for sampling. Our study demonstrates the potential and efficiency of using multi-sensor high-resolution UAS data to constrain the geometry of partially exposed geological units and assist exploration targeting in difficult, poorly exposed terrain.
Chapter
With the rapid development of science and technology, the new generation of aerial photography represented by UAV has been widely used in all walks of life. As an important part of expressway, slope maintenance inspection is always the key and difficult point of road inspection. UAV aerial survey technology has the obvious advantage of high geometric precision and high resolution, and its intervention solves the difficult problems faced by traditional highway survey. In this study, UAV is used for slope maintenance inspection, and the characteristics of UAV, the environment of expressway slope and the problems existing in inspection are analyzed. Based on the current working mode of manual image analysis, the quality of the inspection task is controlled from two aspects of shooting and flight, so as to meet the requirements of the inspectors to interpret the slope state. The research also considers the characteristics of UAV and different types of slope, and selects the algorithm suitable for the slope secondary inspection path planning. The research results of this paper confirm that UAV can effectively solve the problems in image resolution, geometric accuracy of ground objects and flight cost of aerial photogrammetry of large aircraft, and greatly improve the survey efficiency.
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Unmanned aerial vehicle (UAV) photogrammetry one of the most popular photogrammetry technique due to short period of time for data acquisition and low costs compared to the use of classical manned aircrafts. This technique widely been used in many kind of application that related to aerial mapping. This paper review the UAV photogrammetry used for aerial mapping applications. The previous results by others researchers showed the capability of the UAV photogrammetry captures the complex shape and topography. The application for the image processing uses a sequence of 2-dimensional (2D) images to recreate a scene and built it in 3-dimensional (3D) model. The study will utilize the software for 3D models reconstruction which are open source tools and commercial software packages. The study also describe the brief idea to enchance the uses of the UAV photogrammetry in research. End user will have ideas using of the software for photogrammetry.
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Drones have revolutionised the gathering of geoenvironmental data over the last decade. To date, the majority of drone studies of sedimentary rock successions have focussed on well-exposed vertical to subvertical cliff sections. Here, we describe a fundamental method to obtain new data and perspectives on sedimentary successions exposed in partially-obscured foreshore or other horizontal to subhorizontal outcrop surfaces using drones. We illustrate the technique using an example from foreshore exposures of Jurassic strata near Helmsdale, Scotland, UK. Our method aims to make the process of safely collecting drone footage accessible and covers practical considerations from pre-field preparation to data processing. Capturing drone imagery in a foreshore setting involves trade-offs between the time of day which constrains the lighting, the time of year which determines algal cover and tidal range, and the flight time available which indirectly governs image resolution. We show how: (1) orthomosaic images can be used to view sedimentary deposits at different scales and angles enabling identification of large-scale sedimentary features marked by small-scale changes in orientation and lateral variability; (2) production of digital elevation models permits differentially weathered features covered by water or algae to be distinguished, and (3) drones can be used for close up photography of inaccessible features.
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The use of three-dimensional (3-D), photo-textured representations of topography from laser scanning and photogrammetry is becoming increasingly common across the geosciences. This rapid adoption is driven by recent innovations in acquisition hardware, software automation, and sensor platforms, including unmanned aerial vehicles. In addition, fusion of surface geometry with imaging sensors, such as multispectral, hyperspectral, thermal, and ground-based radar, and geophysical methods creates complex and visual data sets that provide a fundamental spatial framework to address open geoscience research questions. Despite the current ease of acquiring and processing 3-D photo-textured models, the accessibility of tools for analyzing and presenting data remains problematic, characterized by steep learning curves and custom solutions for individual geoscience applications. Interpretation and measurement is essential for quantitative analysis of 3-D data sets, and qualitative methods are valuable for presentation purposes, for planning, and in education. This contribution presents LIME, a lightweight and high-performance 3-D software for interpreting and co-visualizing 3-D models and related image data. The software allows measurement and interpretation via digitizing in the 3-D scene. In addition, it features novel data integration and visualization of 3-D topography with image sources such as logs and interpretation panels, supplementary wavelength imagery, geophysical data sets, and georeferenced maps and images. High-quality visual output can be generated for dissemination to aid researchers with communication of their results. The motivation and an overview of the software are described, illustrated by example usage scenarios from outcrop geology, multi-sensor data fusion, and geophysical-geospatial data integration.
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This contribution explores the potential of unmanned aerial systems (UAS) to monitor areas affected by acid mine drainage (AMD). AMD is an environmental phenomenon that usually develops in the vicinity of mining operations or in post-mining landscapes. The investigated area covers a re-cultivated tailing in the Sokolov lignite district of the Czech Republic. A high abundance of AMD minerals occurs in a confined space of the selected test site and illustrates potential environmental issues. The mine waste material contains pyrite and its consecutive weathering products, mainly iron hydroxides and oxides. These affect the natural pH values of the Earth's surface. Prior research done in this area relies on satellite and airborne data, and our approach focuses on lightweight drone systems that enables rapid deployment for field campaigns and consequently-repeated surveys. High spatial image resolutions and precise target determination are additional advantages. Four field and flight campaigns were conducted from April to September 2016. For validation, the waste heap was probed in situ for pH, X-ray fluorescence (XRF), and reflectance spectrometry. Ground truth was achieved by collecting samples that were characterized for pH, X-ray diffraction, and XRF in laboratory conditions. Hyperspectral data were processed and corrected for atmospheric, topographic, and illumination effects using accurate digital elevation models (DEMs). High-resolution point clouds and DEMs were built from drone-borne RGB data using structure-from-motion multi-view-stereo photogrammetry. The supervised classification of hyperspectral image (HSI) data suggests the presence of jarosite and goethite minerals associated with the acidic environmental conditions (pH range 2.3–2.8 in situ). We identified specific iron absorption bands in the UAS-HSI data. These features were confirmed by ground-truth spectroscopy. The distribution of in situ pH data validates the UAS-based mineral classification results. Evaluation of the applied methods demonstrates that drone surveying is a fast, non-invasive, inexpensive technique for multi-temporal environmental monitoring of post-mining landscapes.
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Global Synthetic Aperture Radar (SAR) measurements made over the past decades provide insights into the lateral extent of magmatic domains, and capture volcanic process on scales useful for volcano monitoring. Satellite-based SAR imagery has great potential for monitoring topographic change, the distribution of eruptive products and surface displacements (InSAR) at subaerial volcanoes. However, there are challenges in applying it routinely, as would be required for the reliable operational assessment of hazard. The deformation detectable depends upon satellite repeat time and swath widths, relative to the spatial and temporal scales of volcanological processes. We describe the characteristics of InSAR-measured volcano deformation over the past two decades, highlighting both the technique’s capabilities and its limitations as a monitoring tool. To achieve this, we draw on two global datasets of volcano deformation: the Smithsonian Institution Volcanoes of the World database and the Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics volcano deformation catalogue, as well as compiling some measurement characteristics and interpretations from the primary literature. We find that a higher proportion of InSAR observations capture non-eruptive and non-magmatic processes than those from ground-based instrument networks, and that both transient (< month) and long-duration (> 5 years) deformation episodes are under-represented. However, satellite radar is already used to assess the development of extended periods of unrest and long-lasting eruptions, and improved spatial resolution and coverage have resulted in the detection of previously unrecognised deformation at both ends of the spatial scale (~ 10 to > 1000 km²). ‘Baseline’ records of past InSAR measurements, including ‘null’ results, are fundamental for any future interpretation of interferograms in terms of hazard‚ both by providing information about past deformation at an individual volcano, and for assessing the characteristics of deformation that are likely to be detectable (and undetectable) using InSAR. More than half of all InSAR deformation signals attributed to magmatic processes have sources in the shallow crust (< 5 km depth). While the depth distribution of InSAR-derived deformation sources is affected by measurement limitations, their lateral distribution provides information about the extent of active magmatic domains. Deformation is common (24% of all potentially magmatic events) at loci ≥5 km away from the nearest active volcanic vent. This demonstrates that laterally extensive active magmatic domains are not exceptional, but can comprise the shallowest part of trans-crustal magmatic systems in a range of volcanic settings.
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The advent of large digital datasets from unmanned aerial vehicle (UAV) and satellite platforms now challenges our ability to extract information across multiple scales in a timely manner, often meaning that the full value of the data is not realised. Here we adapt a least-cost-path solver and specially tailored cost functions to rapidly interpolate structural features between manually defined control points in point cloud and raster datasets. We implement the method in the geographic information system QGIS and the point cloud and mesh processing software CloudCompare. Using these implementations, the method can be applied to a variety of three-dimensional (3-D) and two-dimensional (2-D) datasets, including high-resolution aerial imagery, digital outcrop models, digital elevation models (DEMs) and geophysical grids. We demonstrate the algorithm with four diverse applications in which we extract (1) joint and contact patterns in high-resolution orthophotographs, (2) fracture patterns in a dense 3-D point cloud, (3) earthquake surface ruptures of the Greendale Fault associated with the Mw7.1 Darfield earthquake (New Zealand) from high-resolution light detection and ranging (lidar) data, and (4) oceanic fracture zones from bathymetric data of the North Atlantic. The approach improves the consistency of the interpretation process while retaining expert guidance and achieves significant improvements (35–65 %) in digitisation time compared to traditional methods. Furthermore, it opens up new possibilities for data synthesis and can quantify the agreement between datasets and an interpretation.
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We have developed a method employing an autonomous unmanned aerial system (UAS) to provide a more robust measure of the field terrain correction (FTC) for gravity measurements than is offered by traditional methods. The resolution of digital terrain that is typically available for the United States (10 or 30 m) is too low to adequately estimate the FTC in steep terrain. The FTC corresponds to the innermost zone around the gravity station (e.g., extending to a 68 m radius for the Hayford-Bowie zones A and B) and is most often estimated in the field with the aid of templates and charts that approximate sectors of the terrain as uniform slopes. These techniques can incur significant error if they are not performed by experienced practitioners. In our approach, we dispatch a UAS to collect camera images around the gravity station, which we use to construct a digital elevation model (DEM) of the area with the structure from motion (SfM) method. The resulting DEMs allow us to precisely calculate the FTC. We have developed software to automate most of the procedure, including the autonomous flight and image capturing by the UAS. We have experimented with a variety of flight paths at several sites spanning a range of terrain conditions to determine the most efficient flight characteristics for this application. Selecting field sites with existing light detection and ranging data has enabled us to characterize errors in the DEMs derived from SfM and to assess the trade-offs between flight time, processing time, and accuracy of the resulting FTCs. Our methodology is fast (flight time: 3-4 minutes) and robust, primarily because the UAS flight is automated. It can be used to calculate the FTC of a variety of terrain conditions and delivers results that are much more precise than existing methods that do not make use of high-resolution digital terrain data.