Article

Geomorphological and speleogenetical observations using terrestrial laser scanning and 3D photogrammetry in a gypsum cave (Emilia Romagna, N. Italy)

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Abstract

observations using terrestrial laser scanning and 3D photogrammetry in a gypsum cave Abstract Terrestrial Laser Scanning (TLS) and 3D photogrammetry techniques were used in a relatively small (100-m-long) cave developed in Messinian gypsum in Emilia-Romagna (N. Italy). The surveys were carried out to compare the results obtained by both methods in mapping small-to medium-sized morphologies. These measurements allowed reconstructing the evolution stages of the paragenetic (anti-gravitative) morphologies (ceiling channels and pendants) that carved the roof of the cave, and their relationship with local geomorphology, infilling sediments, speleothems, and structural elements. Field measurements were integrated with morphometrical analyses of the digital models that then allowed a much greater number of observations to be made. The results are a clear example of how the combination of TLS and 3D-photogrammetric data can be used to study and measure mm-to dm-scale morphologies in geomorphological studies, including caves, helping to unravel the speleogenetic and, consequently, the hydrological evolution of these environments.

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... Since caves are subsurface formations, it is very difficult to measure caves in detail using classical methods, due to the irregular geometric shapes, high ceilings, and insufficient lighting conditions in caves (Lindgren, Galeazzi 2013). Cave mappings are carried out applying traditional measurement methods, caves are usually represented as longitudinal or cross sections, and the details on the floor of the caves are presented on a 2D map (De Waele et al. 2018). Nowadays, with the low cost of access and the ability to capture a large 3D scene quickly and accurately in a session, highresolution 3D measurement systems such as TLS are being widely adopted for detail-rich cave representation instead of traditional methods. ...
... TLS has become an effective system for producing 3D information about the floor, walls, and ceilings of caves with the ability to collect data in a lightless, complex environment and to produce thousands of 3D points per second (Idrees, Pradhan 2016). There are applications such as 3D modeling and mapping of caves (Gallay et al. 2015;Fabbri et al. 2017), morphological analysis (Fabbri et al. 2017;De Waele et al. 2018), cave stability analysis (Idrees, Pradhan 2018) and understanding of cave systems ( upinský et al. 2022;Hoffmeister et al. 2016) using the TLS measurements. In addition, there are studies in which TLS and terrestrial photogrammetry methods are used together to produce cave models (Pukanská et al. 2020;De Waele et al. 2018). ...
... There are applications such as 3D modeling and mapping of caves (Gallay et al. 2015;Fabbri et al. 2017), morphological analysis (Fabbri et al. 2017;De Waele et al. 2018), cave stability analysis (Idrees, Pradhan 2018) and understanding of cave systems ( upinský et al. 2022;Hoffmeister et al. 2016) using the TLS measurements. In addition, there are studies in which TLS and terrestrial photogrammetry methods are used together to produce cave models (Pukanská et al. 2020;De Waele et al. 2018). In these studies, TLS systems have been shown to provide effective results in extracting detailed 3D information about caves. ...
Article
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The Akçakale cave is a significant natural and cultural heritage site in the Black Sea region of eastern Turkey. The complex geometry and difficult-to-access areas of the cave have made the use of traditional mapping methods challenging. To overcome these limitations, this study utilized TLS and UAV technology to produce highly accurate 2D and 3D data for cave management and risk assessment purposes. The TLS system was used to create a detailed 3D point cloud of the cave interior, while the UAV system generated a 3D model of the surface topography outside the cave. The two sets of data were combined in the GIS environment using a geodetic network established in the study area, providing a common geodetic reference system for both TLS and UAV data. The study found that the cave area is 13,750 m 2 , which is smaller than the area of 18,000 m 2 that was previously estimated using conventional measurement methods. The volume and ceiling heights of the cave were calculated using the elevation models generated from TLS point cloud data. The 3D point cloud data were also used to map dripstone locations on the floor and ceiling of the cave, and the boundaries of rock blocks on the ground were precisely determined. The study identified potential risks associated with the cave, particularly the risk of rockfall in the source rock areas around the cave entrance and the southern part of the cave. The nearest building to the cave is approximately 35 meters away, and all the buildings in the area are less than 300 meters from the cave. In the event of the cave collapse, the buildings in the southern part of the cave are at risk of rockfall. This study demonstrates the effectiveness of combining data from TLS and UAV systems to generate broad and sensitive cave mapping and risk assessment data, which are critical for cave management and safety. The collected data can be used for cave stability investigations and rockfall risk assessments. This study provides a foundation for future explorations of the Akcakale cave and highlights the potential for modern surveying techniques to enhance our understanding of complex geological structures such as caves.
... In addition, the user could move through complex cave passages with the MLS during the acquisition of the 3D point clouds without defining fixed stations, which provided quick and better results to cover the whole cave morphology. On the other hand, the TLS can provide more accuracy and precision due to the series of additional sensors such as an inclinometer, an electronic compass, and a dual-axis compensator (Jacquemyn et al., 2012;Fabbri et al., 2017;De Waele et al., 2018). At least 35 millions of points were acquired for each cave studied. ...
... We processed the point clouds with the open-source software Cloud Compare using the raw file from the LIDAR data. Cloud Compare offers several tools to improve the analysis of cave morphology and geometry (Fabbri et al., 2017;De Waele et al., 2018). MLS data were loaded to plot the intensity values of the scalar field using grayscale. ...
... Fabbri et al. (2017) used TLS to make detailed 3D models for morphometric measurements. De Waele et al. (2018) used TLS and 3D photogrammetry to identify different evolution stages of ceiling channels. Here, we applied both TLS and MLS to observe the karst geometry/shape (Figs. 3 and 7 e, 11 f); the MLS showed more accurate results due to the ability to move the instrument through both narrow and large cave passages without interrupting during acquisition. ...
Article
Caves developed in carbonate units have a significant role in fluid flow, but most of these subsurface voids are below seismic resolution. We concentrated our study on four caves to determine the roles of fractures and folds in the development of karst conduits that may form flow pathways in carbonate reservoirs. We performed structural field investigations, petrographic analyses, and geometric characterization using Light Detection and Ranging (LIDAR) for caves in Neoproterozoic carbonates of the Salitre Formation, central part of the São Francisco Craton, Brazil. We found that the conduit shape, usually with an ellipsoidal cross-section, reflects the tectonic features and textural variations. Carbonate layers containing pyrite and low detritic mineral contents are generally karstified and appear to act as favorable flow pathways. Our results indicate that the development of the karst system is related to fracture corridors formed along parallel and orthogonal sets of fold hinges, which provide preferential pathways for fluid flow and contribute to the development of super-K zones. This study provides insights into the prediction of subseismic-scale voids in carbonate reservoirs, with direct application for the hydrocarbon and hydrogeology flow and storage.
... The cave surface can be modelled from the point cloud as a 3-D polygonal mesh or a 2.5-D raster surface, which was demonstrated in Gallay et al. (2016). Applications of TLS in non-glaciated caves are diverse, comprising the field of geomorphology (Cosso et al., 2014;Silvestre et al., 2014;Idrees and Pradhan, 2016;Fabbri et al., 2017;De Waele et al., 2018), studies on light conditions (Hoffmeister et al., 2014), archaeology (Gonzalez-Aguilera et al., 2009;Rüther et al., 2009;Lerma et al., 2010), and projects aiming to increase awareness and tourism (Buchroithner et al., 2011(Buchroithner et al., , 2012. However, the use of TLS in ice caves is possible but more challenging than in non-ice or exterior environments due to the slippery surface, harsh climate, and physical properties of ice, which absorbs a considerable portion of the shortwave infrared energy typically used by the laser scanner (Kamintzis et al., 2018). ...
... The ice accumulates in an open pit cave formed by the fall of the cave ceiling in lightcoloured Wetterstein limestone sediment between Anisian and Ladinian. The limestone bedding is inclined at 30 • with eastern orientation (Droppa, 1962). Silická l'adnica is classified as a static cave with congelation ice and firn (Luetscher and Jeannin, 2004). ...
... Roda et al. (1974) reported the ice area being from 710 to 970 m 2 and the ice volume being from 213 to 340 m 3 based on ice drilling and considering the precipitation and air temperature during the period before their measurement. Archaeological findings by Kunský, Roth, and Bohm, as reported by Droppa (1962) were used to estimate ice to be 2000 years old. ...
Article
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Ice caves can be considered an indicator of the long-term changes in the landscape. Ice volume is dynamic in the caves throughout the year, but the inter-seasonal comparison of ice dynamics might indicate change in the hydrological–climatic regime of the landscape. However, evaluating cave ice volume changes is a challenging task that requires continuous monitoring based on detailed mapping. Today, laser scanning technology is used for cryomorphology mapping to record the status of the ice with ultra-high resolution. Point clouds from individual scanning campaigns need to be localised in a unified coordinate system as a time series to evaluate the dynamics of cave ice. Here we present a selective cloud-to-cloud approach that addresses the issue of registration of single-scan missions into the unified coordinate system. We present the results of monitoring ice dynamics in the Silická ľadnica cave situated in Slovak Karst, which started in summer of 2016. The results show that the change of ice volume during the year is continuous and we can observe repeated processes of degradation and ice formation in the cave. The presented analysis of the inter-seasonal dynamics of the ice volume demonstrates that there has been a significant decrement of ice in the monitored period. However, further long-term observations are necessary to clarify the mechanisms behind this change.
... And Lidar, which enable the recording of cave geometry. Terrestrial laser scanning techniques (Fabbri et al., 2017) and photogrammetry (De Waele et al., 2018) are commonly employed for 3D cave mapping, extending beyond to the mapping of various cave features as well (Gallay et al., 2015). The data obtained from the 3D representation of caves can be utilized for morphometric analysis by leveraging the point cloud and reconstructing the cave morphology. ...
... When only the sinuosity index is calculated, it refers to sinuosity without regard to its origin and is defined as SI = L c /SD c , where L c represents the conduit length and SD c the shortest air distance (or the straight line) linking the start and the end of the conduit. It may be necessary to subdivide the conduits, based on some parameters, like morphology, to ensure the most accurate calculation of the sinuosity index (De Waele et al., 2018). Another ratio that falls in this category is Asymmetry ratio. ...
Article
Morphometric analysis is the quantification of shapes, which makes irregular shapes found in nature analyzable and comparable. Cave morphometry has been used for the genetic classification of caves, the digital reconstruction of their conduits, the decoding of their paleoenvironment, and other research purposes. Ratios and indices that have been derived from Euclidean geometry and application of fractal geometry onto karst features and topological parameters are the basic methodologies that have been used for shape quantification. This paper reviews the literature that focuses on methodologies used for morphometric analyses and the applications that these methodologies have found.
... In the last decades, a particular attention has been raised on touristic caves and the impact of human presence on the equilibrium of these delicate environments [1][2][3][4]. The contribute of geomatics has become really significant, with the implementation of various 3D mapping methods [5][6][7][8]. 3D modeling can be used for a lot of different purposes that range from tourism to risks assessment. ...
... Anyway, we noticed how the presence of even one GCP (case 2) decrease systematic effects obtained with only PCs (case 3); in fact, residuals on CPs get halved (8. 7 4.8 cm). ...
Chapter
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Nowadays, touristic caves are a relevant topic among topographical and geological studies. Modern techniques allow to elaborate 3D models with high accuracy and precision. Anyway, underground surveys are always delicate to perform, due to narrow and difficult to reach environments. In this paper, we show a case study, "Valdemino" cave, that involved the utilization of different point cloud acquisition methods: UAV, TLS, SLAM. The first purpose was to obtain 3D models of outdoor and indoor environments with a medium and high accuracy. These models were used to calculate the thickness of the rock between surface and cave's roof and will be used for further studies, taking part in the PRIN 2017 project, concerning the impact of the tourist on show caves. The second purpose was to discuss about the feasibility and precision of the different survey methods, when studying a cave. The results showed how SLAM technology is enough accurate for speleological purposes, if compared with the more accurate TLS method. It is precise, maneuverable, easy to use and it allowed to get into environments that TLS can't reach, such as non-touristic areas.
... In the last decade, terrestrial laser scanning (TLS) of caves has been deployed in a range of scientific applications, e.g., archaeology (Burens et al., 2013;Kruger et al., 2016;Landeschi et al., 2019), geology and geomorphology (Silvestre et al., 2015;Fabbri et al., 2017;De Waele et al., 2018), geomorphometry (Gallay et al., 2016), and biospeleology (Azmy et al., 2012;McFarlane et al., 2015). The acquired 3D geometry is also beneficial for mapping and evaluating the ice surface morphology change (Milius and Petters, 2012;Berenguer-Sempere et al., 2014;Š upinský et al., 2019), assessing the natural hazards and collapse susceptibility (Santo et al., 2017;Idrees and Pradhan, 2018), for general visualization and creation of a 3D cave model (Núñez et al., 2013;Cosso et al., 2014), and creating a highly-detailed cave map (Šupinský et al., 2022). ...
... Recent studies demonstrated the applicability of digital photogrammetry for acquiring 3D cave datasets for analysis of morphologies and geological structures, using a digital camera for ground-captured photographs (De Waele et al., 2018) or combined with an unmanned aerial vehicle (UAV) (Triantafyllou et al., 2019). Also, a combination of digital photogrammetry and laser scanning was successfully used in a cave to reveal painted black rock art behind graffiti and moss (Jalandoni et al., 2021). ...
Article
Active remote sensing by laser scanning (LiDAR) has markedly improved the mapping of a cave environment with an unprecedented level of accuracy and spatial detail. However, the use of laser intensity simultaneously recorded during the scanning of caves remains unexplored despite it having promising potential for lithological mapping as it has been demonstrated by many applications in open-sky conditions. The appropriate use of laser intensity requires calibration and corrections for influencing factors, which are different in caves as opposed to the above-ground environments. Our study presents an efficient and complex workflow to correct the recorded intensity, which takes into consideration the acquisition geometry, micromorphology of the cave surface, and the specific atmospheric influence previously neglected in terrestrial laser scanning. The applicability of the approach is demonstrated on terrestrial LiDAR data acquired in the Gouffre Georges, a cave located in the northern Pyrenees in France. The cave is unique for its geology and lithology allowing for observation, with a spectacular continuity without any vegetal cover, of the contact between marble and lherzolite rocks and tectonic structures that characterize such contact. The overall accuracy of rock surface classification based on the corrected laser intensity was over 84%. The presence of water or a wet surface introduced bias of the intensity values towards lower values complicating the material discrimination. Such conditions have to be considered in applications of the recorded laser intensity in mapping underground spaces. The presented method allows for putting geological observations in an absolute spatial reference frame, which is often very difficult in a cave environment. Thus, laser scanning of the cave geometry assigned with the corrected laser intensity is an invaluable tool to unravel the complexity of such a lithological environment.
... Terrestrial laser scanning (TLS) can be considered as a technology suitable for noncontact measurement of spatial coordinates, 3D modeling, and visualization of complex underground structures (Cui et al., 2017;and others). During the last years, terrestrial laser scanning is widely used for the detailed survey of cave spaces and the study of cave morphology (Canevese et al., 2011;Jaillet et al., 2011;Cosso et al., 2014;Gallay et al., 2015Gallay et al., , 2016Silvestre et al., 2015;Oludare Idrees andPradhan, 2016, 2017;Fabbri et al., 2017;De Waele et al., 2018;and others). The high speed of scanning, accuracy, higher productivity versus common geodetic methods (such as selective measurement of individual points by total stations), significant shortening of fieldwork, and automatic data processing into digital models make this technology almost irreplaceable in rapid speleological mapping. ...
... Terrestrial laser scanning (TLS) can be considered as a technology suitable for non-contact measurement of spatial coordinates, 3D modeling, and visualization of complex underground structures (Cui et al., 2017;and others). During the last years, terrestrial laser scanning is widely used for the detailed survey of cave spaces and the study of cave morphology (Canevese et al., 2011;Jaillet et al., 2011;Cosso et al., 2014;Gallay et al., 2015Gallay et al., , 2016Silvestre et al., 2015;Oludare Idrees andPradhan, 2016, 2017;Fabbri et al., 2017;De Waele et al., 2018;and others). The high speed of scanning, accuracy, higher productivity versus common geodetic methods (such as selective measurement of individual points by total stations), significant shortening of fieldwork, and automatic data processing into digital models make this technology almost irreplaceable in rapid speleological mapping. ...
Book
Full-text available
In the presented monograph, we documented the basic research of a geodetic survey of specific irregular surfaces. Based on the research on the behavior of different surfaces, various methods were proposed, and more complex methodological procedures to eliminate the influence of factors negatively affecting the application of non-contact surveying technologies were introduced. As part of the digital modeling of documented surfaces of objects, we tested their applicability, possibilities of various interpolation methods, and modeling techniques in the process of model creation. Technologies such as digital photogrammetry and laser canning bring new opportunities also in the documentation of the Earth’s surface. This combination of technologies allows us to use low-cost digital photogrammetry to document the Earth’s surface in relation to the documentation of geological phenomenon, mining activities, underground spaces, or special industrial applications. The book will also be a good source of information for students, scientists, but also professionals, in their studies, and scientific and professional works.
... SfM is often seen to complement 3D laser scanning adding textural information and photorealism, which is particularly valuable in archaeological contexts (Beraldin et al., 2006;Burens-Carozza et al., 2013;Grussenmeyer et al., 2020;Lerma et al., 2010;Núñez et al., 2013). When the aim is to study karstic morphologies, photogrammetry has also been used in conjunction with TLS for small-scale, highly heterogeneous objects (Pukanská et al., 2020) or for sections where the nature of the underground progression prevents the transportation of TLS equipment (De Waele et al., 2018;Pukanská et al., 2023); here again the studies still primarily rely on LiDAR surveys. Other works have also used SfM techniques to obtain a 3D mesh of the cave's exterior environment, providing a geometric and geological context for the 3D scan, often using drones equipped with on-board cameras (Kruger et al., 2016). ...
Preprint
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Although underground topography methods have significantly evolved in the past two decades, it is still challenging and often costly to create comprehensive 3D models of caves or artificial cavities. Modern methods used by speleologists, involving the generation of a topographic ‘skeleton’ through laser pointer measurements, enable surveying extensive developments but suffer from a lack of resolution. Conversely, the use of Lidar technologies, while capable of obtaining sub-millimeter scans, implies the use of expensive equipment and precision electronics often unsuitable for this harsh underground environment. In this study, we propose to test the use of low-cost cameras (action-cam type) for the complete 3D modeling of a cave through photogrammetry aiming to compare the results with a Lidar survey based on a series of topographic markers precisely measured with a total station. Our findings indicate that photogrammetry is an approach significantly faster and more adaptable in the field, leading to a substantial reduction in artifacts and shadows compared to static Lidar usage. Although post-processing involving image correlation is more computationally intensive for photogrammetry, we explore various strategies to reduce the calculation times. Ultimately, we demonstrate that the residual positioning errors on the topographic markers are of similar centimetric magnitude to those of Lidar. Recent advancements in computing capabilities now make it feasible to consider the use of photogrammetry for extended underground developments, presenting a promising alternative to the more conventionally employed Lidar in such contexts.
... Recent advancements in cave digitisation have facilitated the analysis of archaeological data, enabling the synthesis of spatial analysis tools and complex 3D boundary models across various studies (De Waele et al., 2018;Bayarri et al., 2023;Pan et al., 2023;Pfeiffer et al., 2023;Wisher et al., 2023;Cardia et al., 2024;Kaňuk et al., 2024;Kartini et al., 2024;Oliinyk et al., 2024;Pereira et al., 2024). However, challenges persist in integrating digital technologies into archaeological research, particularly in addressing the complexities of digital models. ...
Article
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In recent years, the field of reality-based 3D model generation has undergone a profound transformation, impacting disciplines such as preservation, archaeology, anthropology, and virtual museums by introducing concepts like virtual heritage and extended reality (XR). The integration of digital models and 3D survey data has become pivotal, enabling immersive experiences and providing unprecedented access to previously inaccessible archaeological sites. In 2022, the Soprintendenza Archeologia, Belle Arti e Paesaggio - Città Metropolitana di Bari embarked on a groundbreaking project to explore Lamalunga cave. This cave, housing a 172,000-130,000-year-old Neanderthal skeleton and 500 faunal remnants, became the focus of an interdisciplinary effort aimed at comprehensively documenting its morphological and typological details alongside the Neanderthal remains. Over a meticulous two-year period, the project meticulously recorded 28 previously undiscovered faunal remains using precise scanning, topographic surveying, and close-range photogrammetry. Central to this endeavor is the Science of Representation, employing advanced 3D modelling techniques such as NURBS algorithms and mesh retopology. These methods facilitated the creation of highly detailed and accurate digital replicas, capturing not only the cave’s intricate physical features but also preserving the contextual integrity necessary for detailed analysis and interpretation of the archaeological findings. This study provides an overview of the digitisation process, examining both the capabilities and limitations of digital models for XR applications. By leveraging cutting-edge technology, this approach enhances preservation, accessibility, inclusivity, and global engagement with one of the world’s most significant Neanderthal sites.
... Nowadays, terrestrial laser scanning (TLS) and 3D photogrammetry techniques are used in caves with archaeological value [17], obtaining data that can be used for 3D modeling [18]. The obtained data can be used for archaeological research and can also help reveal the development process and hydrological evolution of these caves [19]. Ground penetrating radar (GPR) and microgravimetric measurements can be used to map underground karst features [20] or detect buried structures [21]. ...
Article
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The Yunshui Cave in Shangfang Mountain, Beijing, is a famous high-altitude karst cave in northern China. As the third scientific survey of Yunshui Cave in history, this is the first time to use the latest LiDAR technology to carry out a related detection survey. Traditional cave measurement methods are limited by natural conditions and make it difficult to reach the destination. Traditional methods mainly rely on experience and obtain data with strong subjectivity, making it difficult to conduct quantitative research and obtain reproducible results in the current information era. Applying LiDAR technology to cave measurement can obtain comprehensive and accurate digital measurement results within the same survey time and reveal many richer and more accurate features of Yunshui Cave. The obtained digital measurement results can be used for 3D modeling as well as provide a large amount of accurate basic data and preliminary materials for subsequent geological, environmental, and archaeological investigation and analysis, as well as cultural and tourism resource development. The rapid geological survey of Shangfang Mountain Yunshui Cave using LiDAR technology shows that LiDAR cave geological survey technology can achieve real-time collection of centimeter-level accuracy and generate billions of points of cloud data, greatly improving survey efficiency and accuracy. At the same time, digital survey results can be obtained. Through modeling and GIS technology, all on-site survey details can be easily moved back to the laboratory for real-scene reproduction, network sharing, and dissemination. This study provides a foundation for future explorations of the Yunshui cave and highlights the potential for LiDAR techniques to enhance our understanding of complex geological structures such as caves.
... Geomatics' contribution has become extremely substantial, with the widespread implementation of tools and methodologies for different purposes, such as data acquisition, analysis, and geospatial data management. The creation of three-dimensional models allows to understand the spatial distribution of complex and difficult-to-access environments, as well as for geomorphological observation (Dewaele et al., 2018), identification of areas at high risk of structural degradation (Domej et al., 2022) and geomechanical stability assessment (Fazio et al. 2017). Terrestrial laser scanners (TLS) have been widely used to map underground environments and even caves (Idrees and Pradhan, 2016;Castellanza et al. 2018;Giordan et al., 2021;Cardia et al., 2021). ...
Article
Full-text available
Accurate cave surveying is crucial for understanding their genesis, current state, and potential hazards, especially in challenging environments marked by limited accessibility and poor visibility. This study applies geomatics techniques, including Terrestrial Laser Scanning (TLS), SLAM-based Mobile Mapping Systems (MMS), and digital photogrammetry, to create three-dimensional models of artificial caves in Gravina in Puglia, Apulia region, southern Italy. The research aims to assess these methodologies' accuracy, reliability, and performance for structural monitoring and hazard assessment. Despite challenges such as rough conditions, limited accessibility and poor visibility, the study reveals promising insights into the capabilities of these techniques for efficient surveying in complex underground environments. While highlighting the potential of MMS for cost-effective and rapid data acquisition, digital photogrammetry using spherical cameras also emerges as a viable alternative, offering comprehensive data collection capabilities with minimal capture time. Further research is warranted to optimize these techniques for enhanced hazard assessment and structural monitoring in challenging underground environments.
... LIDAR acquisition can be terrestrial (terrestrial laser scanning, TLS) or airborne (airborne laser scanning, ALS). Since photogrammetry and laser scanning are complementary measurement techniques and have applications in many research disciplines, extensive research has already taken place to compare and combine the corresponding datasets (Baltsavias 1999a;Cawood et al. 2017;El-Din Fawzy 2019;Grussenmeyer et al. 2008;Luhmann 2013;Talha and Fritsch 2019;Waele et al. 2018). ...
Article
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Recent flood events (FE) in Germany have shown that the extent and impact of extreme flood events cannot be estimated solely based on numerical models. For analyzing the development of such an event and to develop and implement safety measures more efficiently, additional data must be collected during the event. Within the scope of this research, the possibilities of near real-time recording using an unmanned aerial vehicle (UAV) and data processing with the Structure from Motion (SfM) method were tested in a case study. Different recording parameter combinations were tested in the Laufer Muehle area on the Aisch river in Germany. The focus of the investigations was the identification of a parameter combination that allows a short recording interval for aerial imagery. Based on these findings, the identification of changes in the study area by comparing multitemporal photography (flood prevention), as well as the recording of flooded areas during a FE should be possible. The accuracy analysis of the different parameter combinations between two point clouds as well as the process of change detection was done by a Multiscale Model to Model Cloud Comparison (M3C2) and including ground control points. As a result, a parameter combination was identified which led to the desired results in the study area. The processes were transformed into fully automated and scripted workflows. The results serve as a basis for establishing a workflow for near real-time analyses in future studies.
... Geophysical surveys were supported by 3D terrestrial laser scanning (TLS) and geomorphological surveys. Studies using laser scanning techniques are now widely used due to the possibility of extensive use of the obtained results in environmental, speleological, geological, or geotechnical analyses (e.g., Fekete and Diederichs 2013;Pejić 2013;Fabbri et al. 2017;Zhang et al. 2016;De Waele et al. 2018;Mikita et al. 2020). In the work presented here, the non-invasive nature of the geophysical and laser scanning methods was also important in the choice of these methods so that surveys could be performed over the site and inside it. ...
Article
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The occurrence of subsurface karst caves can cause the development of superficial depressions which, in turn, may pose a construction hazard. Identifying such a substratum requires integrated non-invasive measurement methods. The main objective of the study was to demonstrate the effectiveness of the non-invasive ERT, TLS, and GPR survey techniques in identifying the karst floor and determining the direction of discontinuities around the cave. The paper analyzes the limitations of the methods used in the study of heterogeneous media. These limitations are related to the methodology and measurement conditions, data processing, and interpretation in the context of the resolution and depth range. The study was conducted using the example of the Jaskinia pod Świecami cave, formed in the Sarmatianal calcarenites in Poland. The research confirmed its complex karst-anthropogenic genesis. The cave was formed as a result of the infiltration of rainwater and the dissolution of limestone by groundwater, while the paleokarst forms that are characteristic of it and of the surrounding caves and occur in their vicinity, i.e., narrow ridges called "karst candles", were formed as a result of water circulation during the local permafrost degradation in the middle Pleistocene. However, these forms were modified in the Upper Pleistocene and Holocene, as indicated by ERT images.
... Photogrammetry and terrestrial laser scanners (TLS) have also been increasingly utilized to generate comprehensive 3-dimensional (3D) cave maps, aiding in analysis of archaeological sites, including stratigraphy (Büyüksalih et al., 2020;Núñez et al., 2013). 3D photogrammetry can also be employed in less accessible regions where contemporary laser scanner instruments cannot be physically stationed (Waele et al., 2018). Although scanning devices are generally heavy and very expensive, this technology can produce 3D models of caves quickly and accurately through the captured point clouds (Gallay et al., 2015). ...
Article
Pawon Cave has been studied for over 20 years, however, there is limited accessible spatial data. The feasibility of employing a Terrestrial Laser Scanner (TLS) to reconstruct the archaeological sites has been examined by researchers. TLS observations provide archaeologists with a non-intrusive method of conducting preliminary assessments, reducing the risk of damaging archaeological targets. The purpose of this research is to use TLS to generate a 3D representation of the Pawon Cave. This model not only records and preserves the current structure of the cave but also allows for further in-depth reconstruction of the main hall of Pawon Cave and excavation possibilities. This 3D model substantiates the theory that the sepulchral chamber is isolated from other chambers of the cave and discovers that the main hall of Pawon Cave can accommodate approximately 30 people. This proves the theory that the Pawon Cave may also be used for other activities other than a burial ground.
... These cavities in the subterranean are accessible to human exploration [2], but their mapping is often an arduous task, conditioned by complex environmental factors. Factors such as poor lighting, uneven surfaces, inaccessible areas, narrow pathways and articulated routes represent a challenge for the documentation and digitisation of these underground environments. ...
... A second, direct approach involves understanding and modeling the abiotic and biotic features of subterranean habitats along the vertical dimension. Previous technical gaps hampering the implementation of 3-dimensional modeling in conservation biology have been relaxed by outstanding technological advancements in laser scanning 116,117 , remote sensing 118 , and ecological modeling 119 . Nowadays, information on a representative portion of the vertical dimension of the subterranean environmental matrix can be obtained through a suite of sampling techniques targeting abiotic (e.g., terrestrial laser scanning) and biotic (e.g., pitfall traps, hand collecting, environmental DNA) features [120][121][122] . ...
Article
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Subterranean ecosystems (comprising terrestrial, semi-aquatic, and aquatic components) are increasingly threatened by human activities; however, the current network of surface-protected areas is inadequate to safeguard subterranean biodiversity. Establishing protected areas for subterranean ecosystems is challenging. First, there are technical obstacles in mapping threedimensional ecosystems with uncertain boundaries. Second, the rarity and endemism of subterranean organisms, combined with a scarcity of taxonomists, delays the accumulation of essential biodiversity knowledge. Third, establishing agreements to preserve subterranean ecosystems requires collaboration among multiple actors with often competing interests. This perspective addresses the challenges of preserving subterranean biodiversity through protected areas. Even in the face of uncertainties, we suggest it is both timely and critical to assess general criteria for subterranean biodiversity protection and implement them based on precautionary principles. To this end, we examine the current status of European protected areas and discuss solutions to improve their coverage of subterranean ecosystems.
... Also, the measurement of the massive number of topological features (stalactites) requires high accuracy and high resolution from the used instruments. Although simple ruler measurements and handdrawn maps are still best practice in conventional cave exploring, there are already good examples of the usage of laser scanner in underground scenarios like the scanning of the Eisriesenwelt in Austria (BUCHROITHNER & GAISECKER 2020), Skocjanske cave in Slovenia (WALTERS & HAJNA 2020) or a Messinian gypsum cave in Italy (DE WAELE et al. 2018). In comparison to these surveys, there are some features of the survey in the Katerloch that makes this project special. ...
Conference Paper
Full-text available
This paper describes the 3D survey of an Austrian stalactite cave and the derivation of a Virtual Reality (VR) tour through the data set with the Game Engine Unity. The survey of such a cave beholds many challenges like narrow passages, abstinence of light and scan obstructions in the large stalactite fields. Documenting this huge cave-network required several scanning sessions since the year 2016. The limitations of a cave survey have been overcome by the usage of a broad spectrum of sensors, geodetic total stations, different types of static terrestrial and kinematic laser scanners, SLR cameras and even DJI Mini drones. However, the different surveying techniques deliver varying texture qualities and point accuracies which resulted in inhomogeneous 3D data. Combining these data sets in a common coordinate system and merging them into a single 3D mesh required a solid geodetic reference frame and postprocessing in commercial software products from the laser scanning industry, structure from motion solutions and applications from the entertainment sector. The final 3D model is presented in a VR application as the complexity of the geometry exceeds the capability of the conventional 3D viewers. The user can move along the mesh, has to duck in narrow passages and handles a torch for the exploration of the dark underground. This way students and school pupils get an immersive impression of the dimensions of the cave while they learn about the 3D survey.
... Also, the measurement of the massive number of topological features (stalactites) requires high accuracy and high resolution from the used instruments. Although simple ruler measurements and handdrawn maps are still best practice in conventional cave exploring, there are already good examples of the usage of laser scanner in underground scenarios like the scanning of the Eisriesenwelt in Austria (BUCHROITHNER & GAISECKER 2020), Skocjanske cave in Slovenia (WALTERS & HAJNA 2020) or a Messinian gypsum cave in Italy (DE WAELE et al. 2018). In comparison to these surveys, there are some features of the survey in the Katerloch that makes this project special. ...
... Different approaches have been developed and applied to analyse 3D geomorphological cave structures in order to advance the understanding of their formation and underlying geological processes. De Waele et al. (2018) focused on the reconstruction and analysis of the evolutionary stages of paragenetic morphologies such as ceiling channels and pendants. Hämmerle et al. (2014) tested and investigated the performance of low-cost laser scanning devices for mapping cave features. ...
Article
Full-text available
Perennial ice deposits in caves are an underexplored component of the cryosphere preserving a largely untapped archive of long‐term changes in landscape and climate whose existence is threatened by climate change. This study demonstrates how terrestrial laser scanning (TLS) can be used to fully and accurately (registration accuracy < 1 cm standard deviation of point differences) assess the geometry of an ice‐bearing cave in the Eastern Alps (Tyrol, Austria). Three TLS campaigns and 255 scan positions were used to acquire point clouds with a high sampling density (2 cm average point spacing) in order to minimise shading effects and to assure a precise and highly resolved 3D documentation of the cave. A semi‐automated registration and point cloud‐processing approach adapted to the site‐specific demands ensured a complete and error‐minimised assessment of the cave's geometry serving as a solid basis for future quantifications of snow and ice content dynamics. Dominant cave surface structures were investigated by performing a multiscale principal component analysis (PCA) to identify a detailed and computationally efficient basis for future airflow modelling tasks. Perennial ice deposits in caves are an underexplored component of the cryosphere preserving a largely untapped archive of long‐term changes in landscape and climate whose existence is threatened by climate change. This paper demonstrates how TLS can be used to fully and accurately assess the geometry and snow, respectively ice, content dynamics of an ice‐bearing cave. The semi‐automated registration and point cloud‐processing approach proved successful and represents a solid computational efficient basis for future airflow modelling tasks.
... The LiDAR imaging is a robust tool for observing variations in 3D cave geometry (e.g., Fabbri et al., 2017;De Waele et al., 2018). The 3D models provided by the LiDAR survey (Fig. 3) were used to constrain the dissolution intensity from scallop cave wall profiles and link this parameter with the microtextural and petrophysical properties of lithological units. ...
Article
Understanding the karstification process in fractured carbonates is a key factor in developing and exploiting fractured and karstified reservoirs. This study documents the relationship among the 2D geometry, stratigraphy and petrophysical properties of a cave system developed in a Neoproterozoic mixed carbonate-siliciclastic sequence. We applied a multidisciplinary and multiscale approach that combines structural geological surveys, cave imaging by Laser Detecting and Ranging (LiDAR), linear scanlines, stratigraphic logs, uniaxial compressive strength (UCS), mercury-intrusion porosimetry, and 2D image analysis. We found that bedding-parallel stylolites in dolomitic limestone consist of mm-to cm-thick high-porosity zones (up to 20% measured via 2D image analysis). They acted as fluid conduits that enhanced bedding-parallel dissolution. Field and thin section analyses showed that beds with close spacing and thicker stylolites are more karstified and dissolved than beds showing greater spacing or completely devoid of stylolites, indicating that stylolitic zones act as flow pathways in low porosity-permeability carbonates. Primary porosity, pore size distribution, density and capillary pressure of host rocks have no direct relationship with karstification intensity. We conclude that clusters of burial stylolites may control the hypogenic cave geometry. These findings have direct implications for subsurface permeability prediction in karstified carbonate reservoirs.
... The ability to record and map cave morphology and topology has improved significantly in recent decades Lee 2018;Talha and Fritsch 2019;Waele et al. 2018;Weishampel et al. 2011). The use of terrestrial laser scanning (TLS) enables measurements with high accuracy and relatively short time intervals Gallay et al. 2015). ...
Article
Full-text available
Combining photogrammetric reconstruction (close-range photogrammetry, CRP) and airborne photogrammetry through the structure from motion method (SFM) with terrestrial three-dimensional (3D) laser scanning (TLS), Maelstrom Cave on Big Island, Hawaii (USA), was mapped in three dimensions. The complementary properties of the two methods generated an overall model that depicted significant features of the cave both spatially and visually. Through various processes, the complex geometric quantities were derived from the model that can be used to answer microbiological and climatological questions. In this report, the procedure for the three-dimensional acquisition of the terrain surface above Maelstrom Cave as well as the interior of the cave with TLS and SFM is described. It is shown how the different data sets were combined and contrasted, including a comparison of geometries from the different survey operations. Finally, the editing processes used to quantify and simplify the cave geometry are presented, as well as the analysis of the ellipses generated accordingly to determine the geometric quantities. Through the analysis of the cave geometry, important geometric properties of the Maelstrom Cave could be quantified and categorized. In this way, an effective tool was developed to directly correlate the structure of the cave system with climatological and microbiological parameters in order to answer the corresponding questions.
... LiDAR reduces the amount of time and physical effort involved in cave mapping. It also provides a high level of detail and accuracy that favor geological geometry mapping and modeling (Triantafyllou et al., 2019;Pontes et al., 2021), geomorphological and speleogenetical feature determination (Buchroithner and Gaisecker, 2009;Zlot and Bosse, 2014;Silvestre et al., 2015;Gallay et al., 2015;Fabbri et al., 2017;De Waele et al., 2018;Bella et al., 2022), understanding of hydrological processes (Mahmud et al., 2016(Mahmud et al., , 2018, and archaeology studies (Jaillet et al., 2017;Zeid et al., 2019). ...
Article
Understanding how fractures influence fluid flow in carbonate rocks is essential to understanding karst evolution, oil reservoirs, and aquifer exploitation. The present study investigates karst fracture geometry at the surface and subsurface in the Irecê Basin, a Neoproterozoic epicontinental cratonic basin in the São Francisco Craton, Brazil. We used an Unmanned Aerial Vehicle (UAV) to map both fractures in three outcrops and valley geometries, Light Detection And Ranging (LiDAR) to map 3500 m of cave conduits, and Electrical Resistivity Tomography (ERT) to identify karst zones between 90 and 110 m deep. Our results indicate that the Brejões Karst System comprises of dissolution and collapse features such as caves, dolines, pavements, and karst valley. The quantitative analysis of subseismic fractures (<50 m long) identified 4398 fractures in Outcrop A, 2458 in Outcrop B, 4374 in Outcrop C, and 7172 in 18 cross-sections of the Brejões Cave. These fractures form a corridor with four main sets striking N–S, NNE–SSW, NW–SE, and E–W, where the fracture system is essential to cave connectivity, permeability, and development. The highest frequency of fractures coincides with the main cave axes, where the intersection of the fracture/fault are sites prone to dissolution. The ERT profiles indicated a high density of geophysical anomalies that correspond to enlarged fractures in the epikarstic zone that extend between the surface and approximately 30 m deep. The cave infill impacts the cave characterization and leads to underestimating cave dimensions. This study may contribute to understanding the role played by subseismic scale fractures in karst evolution in gently deformed settings.
... LiDAR reduces the amount of time and physical effort involved in cave mapping. It also provides a high level of detail and accuracy that favor geological geometry mapping and modeling (Triantafyllou et al., 2019;Pontes et al., 2021), geomorphological and speleogenetical feature determination (Buchroithner and Gaisecker, 2009;Zlot and Bosse, 2014;Silvestre et al., 2015;Gallay et al., 2015;Fabbri et al., 2017;De Waele et al., 2018;Bella et al., 2022), understanding of hydrological processes (Mahmud et al., 2016(Mahmud et al., , 2018, and archaeology studies (Jaillet et al., 2017;Zeid et al., 2019). ...
... The LiDAR imaging is a robust tool for observing variations in 3D cave geometry (e.g., Fabbri et al., 2017;De Waele et al., 2018). The 3D models provided by the LiDAR survey (Fig. 3) were used to constrain the dissolution intensity from scallop cave wall profiles and link this parameter with the microtextural and petrophysical properties of lithological units. ...
... The point clouds come from 24 stations, spaced 10 to 20 m apart, and distributed over the entire site with 6 min per station for black and white scanning for 21 stations and 15 min for color scanning for 3 stations. (González Aguilera et al., 2009;Sadier, 2013;Grussenmeyer et al., 2015;Pamart et al., 2019;Melnikova et al., 2015;Leonov et al., 2014;De Waele et al., 2018;Jaillet, 2014;Robert et al., 2014;Maumont, 2010). The range of the used scanner could be up to 70 m, with a vertical rotation of 300 degrees and horizontal of 360 degrees, and approximately 1,000,000 dots/second. ...
Article
Full-text available
From the middle of the 19th century, speleological topography became a discipline, if not an art, which supported the work of both explorers and scientists. Underground explorations in Morocco remain an area to be discovered and developed. The Moroccan 99,890 km² limestone surface, represents 14% of the total surface which potentially contains a large number of caves, only 3 of them are developed. This under-exploitation is explained by the lack of evaluation of the richness of Morocco’s karst and cave heritage, the topographic maps of Moroccan Caves are poorly carried out or absent, the last inventory of Moroccan Caves dates from 1981.The objective of this study is to represent the AZIZA Cave virtually, appreciate its volume, and optimize the topography of the latter based on 3D technologies. Two methods were used, the topography of the cave by a DISTO-X, and the results of the 3D projection of the cave were carried out on the software VISUAL TOPO. Secondly, we carried out 3D modeling by lasergrammetry using a TLS FARO FOCUS 70, to scan the main entrance, the main axes, and the large rooms of the AZIZA Cave, the final rendering was provided by the scene software. Laser grammetry gave us the possibility of having a virtual representation of the cave and also of important details that conventional methods cannot give because of this heritage dimension, conservation conditions are essential, also given the potential to be appreciated that the cave and its environment offer, which can constitute a typical example of the exploitation of karst heritage and its environment.
... LiDAR technology has also proven to be a valuable tool in geological mapping studies (Buckley et al., 2008;Drews et al., 2018), elaboration of digital elevation models (DEMs) (Slob et al., 2002), and virtual outcrop models of hydrocarbon reservoir analogs (Bellian et al., 2005;Enge et al., 2007;Fabuel-Perez et al., 2010;Marques et al., 2020). In 3D cave mappings, ground-based LiDAR data promote a change of perspective in geomorphological studies by allowing the analysis of the morphology and volume of the voids and conduits (Silvestre et al., 2015;Gallay et al., 2016;De Waele et al., 2018) and the analysis of structural and hydrogeological characteristics of the cave bedrock (Buchroithner and Gaisecker, 2009). ...
Article
The present study used a multitool approach to characterize fractures of several orders of magnitude in large fracture corridors, caves, and canyons to investigate their impact on fluid flow in carbonate units. The study area is the Brejões carbonate karst system that is located in the Neoproterozoic Salitre Formation in the Irecê Basin, São Francisco Craton, Brazil. The approach included satellite images, used for interpreting the regional structural context, Unmanned Aerial Vehicle (UAV) and ground-based Light Detection And Ranging (LiDAR) imagery, used for detailed structural interpretation. Regional interpretation revealed that fracture corridors, caves and canyons occur along a hinge of a N–S-oriented anticline. An advanced stage of karstification caused fracture enlargement and intrabed dissolution, and the formation of caves and canyons. A river captured by the highly fractured zone along the anticline hinge played an important role as an erosive agent. Detailed characterization of fracture corridors comprised classic structural analysis, topological studies, persistence estimations, power-law fitting of fracture trace length distributions, and identification of network backbones. Our results indicate that fracture corridors comprise four subvertical fracture sets: N–S and E-W and a conjugate pair, NNE-SSW and NW-SE. Fractures observed in the caves show the same dominant directions. Fracture directions are consistent with a common origin associated with the anticline folding. Fracture traces range from 1.0 m to 300 m, comprising both subseismic (<50 m) and seismic scale fractures (>50 m). Networks have dominance of node terminations Y and X (notably Y), CB values higher than 1.8, high P20 and P21 persistence values, and highly interconnected backbones. Fracture network connectivity is associated with power-law exponents greater than 2.5 for the fracture trace distributions, indicating large influence of subseismic-scale fractures on fluid flow. As the final result of folding and karstification, large volumes of secondary macroporosity were created, particularly in the zone of maximum fracture intensity around the hinge zone of the anticline. This scenario can be used to understand better oil reservoirs formed in similar structural controls in near-surface conditions.
... LiDAR reduces the amount of time and physical effort involved in cave mapping. It also provides a high level of detail and accuracy that favor geological geometry mapping and modeling (Triantafyllou et al., 2019;Pontes et al., 2021), geomorphological and speleogenetical feature determination (Buchroithner and Gaisecker, 2009;Zlot and Bosse, 2014;Silvestre et al., 2015;Gallay et al., 2015;Fabbri et al., 2017;De Waele et al., 2018;Bella et al., 2022), understanding of hydrological processes (Mahmud et al., 2016(Mahmud et al., , 2018, and archaeology studies (Jaillet et al., 2017;Zeid et al., 2019). ...
... Therefore, there are many abandoned positions in the world related to opencast mining conducted in the nineteenth and twentieth centuries, where mining was stopped and the workings were not rehabilitated. The difficulty in defining the principles for revitalisation of these objects is related to the practically unlimited variety of qualitative and quantitative variables describing these objects(De Waele et al., 2018;Hagiou & Konstantopoulou, 2010;Legwaila et al., 2015;Paulo, 2005;Popovi c et al., 2015;Seelen et al., 2021). This was the reason why the conducted research focused on the study of human-environment relations, which is not widely described in relation to post-mining objects. ...
Article
Abandoned mine lands are a common element of the contemporary landscape. In administrative practice, they are rated low, yet they are of interest to informal users and scientific and cultural communities. The aim of the research was to identify the possibilities of using qualitative research methods, applied in architecture, to create friendly, urban spaces with a universal character in the areas of abandoned quarries. The study was conducted in the Sadowa Góra quarry area in southern Poland, using Post Occupancy Evaluation (POE) method. The results of the conducted analysis confirm the effectiveness of the POE method in restoring abandoned mine lands to economically usable state by surveying users' opinions on accessibility, functionality, and visual quality. The applied methodology was used as an effective support for the transformation process of post‐mining areas and as a tool to optimize the costs of their reclamation and maintenance. This article is protected by copyright. All rights reserved.
... In particular, 3D digital models of caves are suitable tools for both scientific purposes. They can be used for geological or geomorphological observations [2], for the integration of 3D underground caves cadastral databases [3], and visualization and navigation, especially related to complex access caves, through virtual and augmented reality techniques [4]. In geomatics, several well-established methods are available for the three-dimensional survey of environments. ...
Article
Full-text available
A three-dimensional survey of natural caves is often a difficult task due to the roughness of the investigated area and the problems of accessibility. Traditional adopted techniques allow a simplified acquisition of the topography of caves characterized by an oversimplification of the geometry. Nowadays, the advent of LiDAR and Structure from Motion applications eased three-dimensional surveys in different environments. In this paper, we present a comparison between other three-dimensional survey systems, namely a Terrestrial Laser Scanner, a SLAM-based portable instrument, and a commercial photo camera, to test their possible deployment in natural caves survey. We presented a comparative test carried out in a tunnel stretch to calibrate the instrumentation on a benchmark site. The choice of the site is motivated by its regular geometry and easy accessibility. According to the result obtained in the calibration site, we presented a methodology, based on the Structure from Motion approach that resulted in the best compromise among accuracy, feasibility, and cost-effectiveness, that could be adopted for the three-dimensional survey of complex natural caves using a sequence of images and the structure from motion algorithm. The methods consider two different approaches to obtain a low resolution complete three-dimensional model of the cave and ultra-detailed models of most peculiar cave morphological elements. The proposed system was tested in the Gazzano Cave (Piemonte region, Northwestern Italy). The obtained result is a three-dimensional model of the cave at low resolution due to the site’s extension and the remarkable amount of data. Additionally, a peculiar speleothem, i.e., a stalagmite, in the cave was surveyed at high resolution to test the proposed high-resolution approach on a single object. The benchmark and the cave trials allowed a better definition of the instrumentation choice for underground surveys regarding accuracy and feasibility.
... This area is well known for its natural and scientific interest (see Fig. 1). The Ca' Castellina gypsum cave is located at the bottom of the nearby doline immediately West of the quarry, and is an important palaeoclimatic and palaeoenvironmental site witnessing the hydrology and sedimentation occurred previous to the Last Glacial Maximum (De Waele et al., 2018). Another important archaeological cave, the Grotta dei Banditi, opens on the southern slopes of Mt. ...
Article
Roman-period extractive sites in gypsum outcrops are very rare, and most have become very degraded by later weathering or quarrying activities. This paper describes, using laser scanning, photogrammetry and survey using a UAV-based survey, the uniquely well-preserved Roman-period gypsum quarry of Ca’ Castellina (Northern Apennines, Italy). This site was excavated only in the last few years and the excavations have brought to light some gypsum blocks and the ancient quarry benches showing excavation marks, the remains of a rectangular building and a great number of artefacts that range between the Protohistoric Period and the modern times. The size of the extracted blocks, the extraction methodologies and the age of a charcoal fragment (361 – 178B CE) found immediately at the contact between the gypsum quarry floor and the infilling sediments date the quarry back to the Roman age. Archaeological evidences demonstrate the building to have been used for a short period of time during the XVI-XVII century. Immediately after its abandonment most of the quarry floor has been covered with a thick detrital layer, protecting it from dissolution (fossilizing this floor and leaving it as if it was abandoned very recently), whereas the naked or poorly covered floor of this quarry has been subjected to dissolution phenomena of the exposed gypsum rocks, with a lowering of the surface, the smoothening of the corners and the formation of a set of deeply carved karren features. A 3D survey using both a laser scanning instrument and a drone-mounted photo camera have allowed to get precise measures on the size of the blocks that were extracted in this quarry, the traces of pick axe marks, and on the dissolution morphologies that have developed on the bare gypsum rock. These typical gypsum landforms show how fast these solution forms can develop where concentrated runoff flows on bare gypsum. To prevent this exceptional archaeological extractive site of being further dissolved, it will be important to plan some measures to be put in place in order to protect this delicate historical landmark.
... For the purposes of this study, GeoSLAM is superior to conventional terrestrial laser scanning because it does not require the bulky equipment and cumbersome setups that are ill suited for cave environments, where narrow and tortuous passages make stop-and-scan strategies difficult. Such systems are, however, possibly adapted for smaller caves or specific parts of larger caves (De Waele et al., 2018). ...
Article
The Morro Vermelho Cave (MVC) (Brazil) developed within the Morro Vermelho karst system, which affected Neoproterozoic limestones (Salitre Formation). The MVC experienced little interactions with meteoric processes and is an example of a hypogenic cave formed during strike-slip deformation. The Salitre carbonates in the MVC experienced distributed deformation along an elongated domain overlying a buried strike-slip fault. Gently dipping, semiductile shear zones formed with decimeterscale (3.9 in.) dolomitic veins. In our model, Mg-rich fluids flowing along the Salitre aquifer caused at the same time extensive dolomitization of the body of rock (100-m [328-ft] scale) experiencing distributed deformation. With progressive displacement, the deep strike-slip fault propagated upward causing the development of an anticline pop-up, steepening sedimentary layers, and steep 1–10-m-long (3.3–33.8-ft) fractures, which served as pathways for upward fluid flow. These steep extensional fractures made it possible for fluids flowing in lower, quartzitic aquifers to enter the carbonate aquifer causing silica deposition in rock cavities and in fractures and fault planes. Following the main stage of speleogenesis, silica deposition took over again depositing on the cave walls a continuous silica crust, rarely observed in other settings worldwide. The interplay between regional beddingparallel flow and focused circulation of fluids along steep faults and dipping layers, and the associated rock–fluid interactions are not unique to the contractional settings presented but can also occur in association with similar faults in rifted continental margins.
... Terrestrial Laser Scanning (TLS) can be considered as a technology suitable for non-contact measurement of spatial coordinates, 3D modeling, and visualization of complex underground structures ( [18] and others). During the last years, terrestrial laser scanning has been widely used for the detailed survey of cave spaces and the study of cave morphology ( [19][20][21][22][23][24][25][26][27][28] and others). The high speed of scanning, accuracy, higher productivity versus common geodetic methods (such as selective measurement of individual points by total stations), significant shortening of fieldwork, and automatic data processing into digital models make this technology almost irreplaceable in rapid speleological mapping. ...
Article
Full-text available
The Ochtiná Aragonite Cave (Slovakia, Central Europe) is a world-famous karst phenomenon of significant geological, geomorphological, and mineralogical values. Its specific origin is determined by particular lithological and hydrogeological conditions of the Ochtiná karst formed in lenses of Paleozoic crystalline limestones, partly metasomatically altered to ankerite and siderite. Although the cave is only 300 m long, it represents a combined labyrinth consisting in parallel tectonically controlled halls and passages, that are largely interconnected through transverse conduits of phreatic and epiphreatic morphology with many medium-and small-scale forms originated in slowly moving or standing water (flat solution ceilings, wall inward-inclined facets, water table notches, convectional cupolas, and spongework-like hollows). The highly dissected and irregular morphologies of the cave were surveyed with terrestrial laser scanning and digital photogrammetry. Both used surveying technologies proved to be suitable for quick and accurate mapping of the complicated cave pattern. While terrestrial laser scanning can provide a rapid survey of larger and more complex areas with results delivered directly in the field, digital photogrammetry is able to generate very high-resolution models with quality photo-texture for mapping of small-scale morphologies. Several data on cave morphometry were generated from terrestrial laser scanning (e.g., the area of cave ground plan, the peripheral surface of underground spaces, and their volume). The new detailed map, sections, and 3D model create an innovation platform for a more detailed study on the morphology and genesis of this unusual cave also for its environmental protection and use in tourism.
... Typically conducted using only consumergrade cameras, DEM built from SfM-MVS photogrammetry employs highly portable sensors, which is a key consideration for many applications, such as extraterrestrial field surveys (Caravaca et al., 2019), mapping of caves and mines (e.g. De Waele et al., 2018;Triantafyllou et al., 2019), or in challenging/poorly accessible exposures (Bistacchi et al., 2015;Giuffrida et al., 2020). The low cost of consumer-grade cameras has had a transformative impact upon the uptake of close-range remote sensing within the geosciences, providing an egalitarian approach to DEM generation, which is practically available to all. ...
Article
Smartphones can be regarded as cameras, natively equipped with geolocation and orientation sensors, making them powerful, portable, user-friendly and inexpensive tools for terrestrial structure from motion/multiview stereo photogrammetry (SfM-MVS) surveys. Camera extrinsic parameters (i.e. camera position and orientation), required to produce fully georeferenced SfM-MVS 3D models are available for the majority of smartphone images via inbuilt magnetometer, accelerometer/gyroscope, and global navigation satellite system (GNSS) sensors. The precision of these internal sensors is not yet sufficient to directly use them as input to SfM-MVS photogrammetric reconstructions. However, when the reconstructed scene is significantly greater than the positional error, camera extrinsic parameters can be successfully used to register 3D models during post-processing. We present a survey of a 400 m wide vertical cliff to illustrate a workflow that enables the use of smartphone cameras to generate and fully georeference photogrammetric models without employing ground control points. Survey images were acquired at a distance of ~350 m to the mapped scene using a consumergrade smartphone. This survey image dataset was subsequently used to build an unreferenced 3D model, which was registered during postprocessing using orientation and position metadata tagged to each photograph. This ms has been accepted for publication in the journal Geomorphology
... Since the image processing is almost automatic (James and Robson, 2012), little expertise needs to use 3D-PR techniques. Furthermore, recent applications in soil erosion (Castillo et al., 2012;Gómez-Gutiérrez et al., 2014;Kaiser et al., 2014;Di Stefano and Ferro, 2016) or in cave morphologies (De Waele et al., 2018) demonstrated that high accurated DTMs can be obtained. The use of Structure from Motion (SfM) technique is integrated with MultiView-Stereo (MVS) workflows (Seiz et al., 2006;Westoby et al., 2012;Javernick et al., 2014) in software packages such as Photoscan (Agisoft) (Frankl et al., 2015). ...
Article
Rillenkarren are small scale, straight, narrow solution channels that head at the crest of a bare rock slope and are extinguished downslope. In this paper the applicability of 3D-photo reconstruction technique of the rock surface is proposed for capturing the rillenkarren morphometry on gypsum. At first, the measurements are used to assess a relationship between the width/depth ratio and the depth of the rillenkarren. The exponent of this power relationship resulted different from the theoretical value - 0.5, confirming that the cross-section profiles of a rillenkarren can have a shape different from parabolic. The analysis developed for the cross-section area, the perimeter and the hydraulic radius established that the formation process is able to deep and enlarge the channel. The proposed model of the measured longitudinal profiles confirmed that the profile shape can be characterized by a flex point which divide the upstream concave part from the downstream convex one. According to previous studies on soil erosion features (rills, ephemeral gullies and gullies) the relationship between the rillenkarren length and its volume was expressed by a power equation. The comparison between rillenkarren and soil erosion features allowed to conclude that a single exponent (equal to 1.1) can be applied while the coefficient is characteristic of the feature and represents the influence of channel depth and width. Finally a model of rillenkarren morphometry, deduced applying the dimensional analysis and self-similarity, was applied to the measurements. This analysis demonstrated that a single dimensionless relationship is applicable to rillenkarren and rills, ephemeral gullies and gullies, assessing that a morphometric similarity exists between these different erosion features.
... The advantage of using passive sensors is that they do not require elaborate data acquisition planning, and data processing is also very easy for non-expert operators. Some recent studies described the application of 3D photogrammetric techniques on small areas of dark caves [6,21,22] or as an integration into the terrestrial laser scanning (TLS) approach [23]. ...
Article
Full-text available
The geomatic survey in the speleological field is one of the main activities that allows for the adding of both a scientific and popular value to cave exploration, and it is of fundamental importance for a detailed knowledge of the hypogean cavity. Today, the available instruments, such as laser scanners and metric cameras, allow us to quickly acquire data and obtain accurate three-dimensional models, but they are still expensive, require a careful planning phase of the survey, as well as some operator experience for their management. This work analyzes the performance of a smartphone device for a close-range photogrammetry approach for the extraction of accurate three-dimensional information of an underground cave. The image datasets that were acquired with a high-end smartphone were processed using the Structure from Motion (SfM)-based approach for dense point cloud generation: different image-matching algorithms implemented in a commercial and an open source software and in a smartphone application were tested. In order to assess the reachable accuracy of the proposed procedure, the achieved results were compared with a reference dense point cloud obtained with a professional camera or a terrestrial laser scanner. The approach has shown a good performance in terms of geometrical accuracies, computational time and applicability.
... Terrestrial laser scanners (TLSs) have been extensively used in underground environments for a wide spectrum of applications, ranging from archaeology to geomorphology, from palaeontology/paleoclimatology to ecology/biology and visualization and education (Fabbri et al., 2017;Mohammed Oludare & Pradhan, 2016). Examples of photogrammetric surveying have also been reported in the literature, in comparison (Pukanská et al., 2017) or combination with TLS (De Waele et al., 2018;Rodríguez-Gonzálvez et al., 2015). Recently, fisheye lenses have been successfully employed in natural (Alessandri et al., 2019) and man-made narrow spaces (Perfetti et al., 2017). ...
Article
Full-text available
Underwater caves represent the most challenging scenario for exploration, mapping and 3D modelling. In such complex environment, unsuitable to humans, highly specialized skills and expensive equipment are normally required. Technological progress and scientific innovation attempt, nowadays, to develop safer and more automatic approaches for the virtualization of these complex and not easily accessible environments, which constitute a unique natural, biological and cultural heritage. This paper presents a pilot study realised for the virtualization of 'Grotta Giusti' (Fig. 1), an underground semi-submerged cave system in central Italy. After an introduction on the virtualization process in the cultural heritage domain and a review of techniques and experiences for the virtualization of underground and submerged environments, the paper will focus on the employed virtualization techniques. In particular, the developed approach to simultaneously survey the semi-submersed areas of the cave relying on a stereo camera system and the virtualization of the virtual cave will be discussed.
... All of the caves show the typical configuration of epigenic gypsum caves, appearing as simple horizontal tunnels connected to lower or upper levels (if present) by vertical shafts (Klimchouk et al., 1996). The planimetry of the caves follows the WNW-ESE Apennine-like and the NE-SW anti-Apennine like directions (Ghiselli et al., 2011), a common feature in the Romagna sector (De Waele et al., 2018a). ...
Article
High-resolution U-Th and 14C dating of two calcite flowstones (RTf: Last Interglacial; RTy: Late Holocene) from the Re Tiberio – Monte Tondo karst system (North Italy) is presented to investigate the palaeoclimate potential of speleothems from gypsum caves. To date, there is a lack of information regarding the dating potential of calcite speleothems that have grown in such gypsum karst environment (e.g. no pseudokarst). High-resolution U-Th dating, aimed at establishing if these speleothems can provide robust radiometric age sequences, is first presented. Although both samples show promise for reliable radiometric dating, about 20% of the ages in the RTf dataset were excluded from the age-model as outliers. These outliers are best explained by post-depositional diagenetic processes affecting the U-Th system rather than anything specific to gypsum karst environment conditions. In contrast, outliers were not detected in the RTy sample, but U-Th analysis was not able to constrain its relatively young age (∼600 years before present, B.P.). Consequently, radiocarbon measurements were undertaken, and combined with the U-Th ages to build an age-model. The latter allowed the estimation of “dead carbon fraction” (DCF), which yields a constant value through time, and a magnitude comparable to other sites where climate is similar to Monte Tondo. Soils were considered the main source of carbon, because bedrock dissolution acted predominantly under open-system conditions, and soil organic matter (SOM) turnover rate appears above average compared to sites studied elsewhere.
... This makes measurement of slender, overhanging or highly complex objects difficult and likely to be under-estimated in terms of their rugosity, even if additional time is spent moulding the chain to complex/overhanging surfaces. The SfM technique shares this limitation of typically not being able to fully capture overhanging surfaces, however incorporating an increased number of oblique angle or upwards facing photos where possible (with appropriate lighting) will minimize this limitation and can allow vertical structures to fully overhanging cave systems to be imaged using SfM (Hernández et al., 2016;Robert et al., 2017;De Waele et al., 2018). ...
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Reef structural complexity provides important refuge habitat for a range of marine organisms, and is a useful indicator of the health and resilience of reefs as a whole. Marine scientists have recently begun to use ‘Structure from Motion’ (SfM) photogrammetry in order to accurately and repeatably capture the 3D structure of physical objects underwater, including reefs. There has however been limited research on the comparability of this new method with existing analogue methods already used widely for measuring and monitoring 3D structure, such as ‘tape and chain rugosity index (RI)’ and graded visual assessments. Our findings show that analogue and SfM RI can be reliably converted over a standard 10-m reef section (SfM RI = 1.348 x chain RI—0.359, r2 = 0.82; and Chain RI = 0.606 x SfM RI + 0.465) for RI values up to 2.0; however, SfM RI values above this number become increasingly divergent from traditional tape and chain measurements. Additionally, we found SfM RI correlates well with visual assessment grades of coral reefs over a 10 x 10 m area (SfM RI = 0.1461 x visual grade + 1.117; r2 = 0.83). The SfM method is shown to be affordable and non-destructive whilst also allowing the data collected to be archival, less biased by the observer, and broader in its scope of applications than standard methods. This work allows researchers to easily transition from analogue to digital structural assessment techniques, facilitating continued long-term monitoring, whilst also improving the quality and additional research value of the data collected.
... For these reasons, TLS devices are often used in challenging environments like tunnels, galleries and hypogeal spaces. Due to their technical characteristics, they are useful to create highresolution 3D maps of underground areas such as natural caves, for geomorphological investigations, and to carry out measurements on hypogeal environments to document them as in (De Waele et al., 2018) and (Fabbri et al., 2017). As proposed in (Serna et al., 2015) the integration of 3D model from TLS and images makes possible the combining of geometric accuracy and texture quality allowing to reach a high level of photorealism. ...
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Italian Cultural Heritage is rich in fascinating Underground Heritage (UH) to be protected and preserved because of its fragility and historical importance. An accurate and high-resolution 3D model is essential to reach an appropriate level of knowledge to safeguard caves but there are several obstacles to face. Underground data acquisition and following elaborations are problematic due to environmental conditions such as lack of homogeneous light sources, highly absorbing and unstable surfaces, narrow spaces and complex geometry. For these reasons, the integration of different techniques is mandatory to achieve a valid final product that could be an important basis for consolidation, preservation and valorization of the UH. In this paper, an integrated survey method is tested for a realistic digital reconstruction of hypogeal spaces. In addition to outputs for experts of conservation, the creation of multimedia products for a wider audience of non-professionals users is investigated as a way to preserve UH from decay. Thanks to VR, visitors virtually walk through the underground galleries observing and interacting, making accessible also fragile environments with forbidden access due to preservation policies.
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The authors present a new approach to mapping hard-to-reach caves. It relies on a modern framework of ground-based stereo photogrammetric and geodetic surveying, aerial photography from UAVs and computer modelling. A stereo system was designed and assembled, consisting of two GoProHero9 Black cameras and a powerful artificial light source with diffusing lens, mounted on the operator`s helmet. The site for underground filming was the Syanovskaya quarry (Moscow oblast, Domodedovo rayon). The aerial survey of the cave ground part was also made with DJIAir 2S UAV; it included a ravine with a concrete well, which was the entrance to the quarry. The article deals with the processes of geodetic georeferencing, external orientation of the surface model and underground parts of the cave, as well as the cartographic materials obtained in the course of the work
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In recent years, the application of real scene 3D technology has become widespread in urban planning and cultural heritage protection. However, there has been relatively little attention paid to the construction of real scene 3D models for special natural landscapes such as caves. Given the global distribution of karst topography and the large number of naturally developed caves with diverse types, unique landscape styles, and significant scientific value, this paper enriches the research in this field. By combining ground-based and aerial remote sensing techniques, and based on 3D laser scanning and photogrammetry, we have successfully constructed a real scene 3D model of the internal structure of a karst cave with a precision better than 4 cm. Utilizing Unmanned Aerial Vehicle (UAV) oblique photography, we established a real scene 3D model of the external karst landform with a precision better than 2 cm. We also integrated the internal and external 3D models of the cave, developing a new, complete, and high-precision method for constructing real scene 3D models of karst cave landscapes. Furthermore, we proposed a method for texture reproduction in the dark environment inside the caves, enhancing the reproduction and visual appeal of the real interior. The establishment of high-precision real scene 3D models can not only serve as an effective tool for scientific research on caves but also, as replicas of the real world, play a crucial role in public dissemination and education, thereby enhancing public understanding of cave geological landscapes.
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Chapter
This chapter deals with the morphology of the subterranean world accessible to human beings: caves. It also focuses on the gross morphology of dissolution caves, which are the great majority of the caves on Earth. Many geomorphology textbooks adopt a process‐landform‐based approach to describe the different types of geomorphic features, grouping them according to the most common zonal or azonal geomorphic system in which they develop. Caves can form by a variety of processes, which can be categorized into the following groups: dissolution, weathering and erosion, mechanical movement and accumulation, deposition, melting, and solidification. The roofs, walls, and floors of cave passages can be sculpted by medium‐ to small‐scale morphological features formed by solution and mechanical erosion, collectively designated as speleogens. These morphologies carved in the rock can provide valuable information on the processes that were active in the cave passages, especially in the latest (more recent) stages of their development.
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Topography is the most important component of the geographical shell, one of the main elements of geosystems, and the framework of a landscape. geomorphometry is a science, the subject of which is modeling and analyzing the topography and the relationships between topography and other components of geosystems. Currently, the apparatus of geomorphometry is widely used to solve various multi-scale problems of the Earth sciences. As part of the RFBR competition “Expansion”, we present an analytical review of the development of theory, methods, and applications of geomorphometry for the period of 2016–2021. For the analysis, we used a sample of 485 of the strongest and most original papers published in international journals belonging to the JCR Web of Science Core Collection quartile I and II (Q1–Q2), as well as monographs from leading international publishers. We analyze factors caused a progress in geomorphometry in recent years. These include widespread use of unmanned aerial survey and digital photogrammetry, development of tools and methods for survey of submarine topography, emergence of new publicly available digital elevation models (DEMs), development of new methods of DEM preprocessing for their filtering and noise suppression, development of methods of two-dimensional and three-dimensional visualization of DEMs, introduction of machine learning techniques, etc. We consider some aspects of the geomorphometric theory developed in 2016–2021. We discuss new computational methods for calculating morphometric models from DEM, as well as the problems facing the developers and users of such methods. We consider application of geomorphometry for solving multiscale problems of geomorphology, hydrology, soil science, geology, glaciology, speleology, plant science and forestry, zoogeography, oceanology, planetology, landslide studies, remote sensing, urban studies, and archaeology.
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The Natzweiler-Struthof camp is the only concentration camp in France, in Alsace. In 1941, when the construction of this camp began, the Nazi regime had already set up several concentration camps in annexed territory. The purpose of this camp was mainly to intern the resistance considered dangerous for the regime. From a chronological point of view, the camp integrated in May 1941 its first prisoners. They were condemned to carry out inhumane work until the evacuation of the camp on September 2, 1944. The Natzweiler-Struthof camp was associated with a granite quarry where we can still find concrete foundations of old buildings as well as three galleries excavated with explosives. The digitization work aims to archive, analyze and understand the organization and operation to result in a 3D reconstruction of the site. In 2018, the Struthof site began a major restoration project. For the first time in this camp, an archaeological diagnosis was then made with the aim of understanding the still existing facilities and assuming the presence of other elements now destroyed. To deepen the knowledge on this camp, the Regional Administration of Cultural Affairs authorized in 2020 to carry out prospecting accompanied by a study of the built-up in an area still empty of research: the quarry. Currently, this part of the camp shows the remains of three buildings and three galleries. To know more about these elements and indirectly about the life of the camp and its prisoners, this study shows the approach adopted to prepare the 3D modeling of buildings and galleries.
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Eye-Dome Lighting (EDL) is a non-photorealistic, image-based shading technique designed to improve depth perception in scientific visualization images. It relies on efficient post-processing passes implemented on the GPU with GLSL shaders in order to achieve interactive rendering. Solely projected depth information is required to compute the shading function, which is then applied to the colored scene image. EDL can, therefore, be applied to any kind of data regardless of their geometrical features (isosurfaces, streamlines, point sprites, etc.), except to those requiring transparency-based rendering.
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Terrestrial LIDAR (T-Lidar, or 3-D) scanning gives outstanding detail in cave surveying, generating extremely large datasets of dense point clouds, resulting in very detailed and precise 3D models of the scanned caves. These models are commonly used to determine the volume of chambers. Intuition tells us that the denser the point cloud, the better it will fit the real dimensions of the cave. Here we prove that this is not the case. We show that with a low number of measured points it is possible to calculate volumes which will match the true volumes of a cavity with high precision. Scanning at extremely coarse resolution with angles as high as 4.3° (approximately 1/400 of full resolution) gives a good estimate of volume, although detail is not rendered. The linear relationship between the distance of the scanner and the scanned resolution of the cave wall indicates that < 1 cm-scale detail can be rendered by scanning at ¼ resolution up to ~20 m distance. For the same detail, at distances between ~20 and ~70 m, scanning at higher resolution will be required. It is not possible, even with full resolution, to get centimetre-scale detail at distances greater than ~70 m. Therefore, it is apparent that scanning caves at only ¼ resolution is generally quite sufficient to represent the real volume of the cave and most of the detail.
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As part of activities of the " Inside the Glaciers " project, managed by an Italian team of speleologists and geologists with the purpose of studying several ice-caves in Europe and South America, a research campaign was recently carried out in Mount Etna (Sicily, Italy). This volcano is the highest active in Europe and hosts more than 200 caves including Grotta del Gelo (Ice Cave) which is located on the Northern flank of Mount Etna at an altitude of about 2040 m a.s.l. This cave was formed during the Etna's long and most destructive eruption dated from 1614 to 1624 and is one of the most famous because it hosts a small glacier, maybe the southernmost of the Northern hemisphere. Aim of this project was to realize a detailed survey of Grotta del Gelo using a Leica HDS 7000 terrestrial laser scanner in order to acquire precise data measurements of the ice deposits. This survey was the first step of a monitoring project that will be developed in the next years in collaboration with the Etna Regional Park, the Sicilian Regional Speleological Federation and the Centro Speleologico Etneo of Catania which by many years are involved in the topographic monitoring of this particular cave. The proposed article introduces the methods used for this first laser scanning survey campaign of Grotta del Gelo and the results obtained.
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Although outcropping rarely in Italy, evaporite (gypsum and anhydrite) karst has been described in detail since the early 20 th century. Gypsum caves are now known from almost all Italian regions, but are mainly localised along the northern border of the Apennine chain (Emilia Romagna and Marche), Calabria, and Sicily, where the major outcrops occur. Recently, important caves have also been discovered in the underground gypsum mines in Piedmont. During the late 80s and 90s several multidisciplinary studies were carried out in many gypsum areas, resulting in a comprehensive overview, promoting further research in these special karst regions. More recent and detailed studies focused on the gypsum areas of Emilia-Romagna and Sicily. Sinkholes related to Permian-Triassic gypsum have been studied in Friuli Venezia Giulia. This article reviews the state of the art regarding different aspects of evaporite karst in Italy focusing on the main new results.
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has traditionally been undertaken by tacheometric surveying methods. These methods are excellent for capturing the general shape of a cave system but they are not suitable for high-speed, high-resolution mapping of complex surfaces found in this environment. Terrestrial laser scanning (TLS) technologies can acquire millions of points represented by 3-D coordinates, at very high spatial densities on complex multifaceted surfaces within minutes. In the last few years, advances in measurement speed, reduction in size / cost and increased portability of this technology has revolutionised the collection of 3-D data. This paper discusses the methodological framework and the advantages / disadvantages of adopting terrestrial laser scanning to rapidly map a complex cave system on the example of the Domica Cave in Slovakia. This cave originated in the largest karst region in the West Carpathians. The collected data set or ‘point cloud’ contains over 11.9 billion of measured points, captured in 5 days from 327 individual scanning positions. The dataset represents almost 1,600 m of the cave passages. Semi-automatic registration of these scans was carried out using reference spheres placed in each scene and this method archived an overall registration error of 2.24 mm (RMSE). Transformation of the final registered point cloud from its local coordinate system to the national cartographic system was achieved with total accuracy of 21 mm (RMSE). This very detailed data set was used to create a 3-D cave surface model needed for volumetric analyses. In the future, it will be used for spatial analyses or simulating the interaction of surface and subsurface processes contributing to the development of the cave system on the basis of a 3-D GIS platform.
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Gypsum beds host the majority of the caves in the north-eastern flank of the Apennines, in the Emilia Romagna region (Italy). More than six hundred of these caves have been surveyed, including the longest known epigenic gypsum cave systems in the world (Spipola-Acquafredda, ~11 km). Although this area has been intensively studied from a geological point of view, the age of the caves has never been investigated in detail. The rapid dissolution of gypsum and uplift history of the area have led to the long-held view that speleogenesis commenced only during the last 130,000 years. Epigenic caves only form when the surface drainage system efficiently conveys water into the underground. In the study area, this was achieved after the dismantling of most of the impervious sediments covering the gypsum and the development of protovalleys and sinkholes. The time necessary for these processes can by constrained by understanding when caves were first formed. The minimum age of karst voids can be indirectly estimated by dating of the infilling sediments. U-Th dating of carbonate speleothems growing in gypsum caves has been applied to 20 samples from 14 different caves from the Spipola-Acquafredda, Monte Tondo-Re Tiberio, Stella-Rio Basino, Monte Mauro, and Castelnuovo systems. The results show that: i) caves were forming since at least ~600 kyrs ago; ii) the peak of speleogenesis was reached during relatively cold climate stages, when rivers formed terraces at the surface and aggradation caused paragenesis in the stable cave levels; iii) ~200,000 years were necessary for dismantling of most of the sediments covering the karstifiable gypsum and the development of a surface mature drainage network. Besides providing a significant contribution to the understanding of evaporite karst evolution in the Apennines, this study refines our knowledge on the timescale of geomorphological processes in a region affected by rapid uplifting.
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The change of hydrological conditions during the evolution of caves in carbonate rocks often results in a complex subterranean geomorphology, which comprises specific landforms such as ceiling channels, anastomosing half tubes, or speleothems organized vertically in different levels. Studying such complex environments traditionally requires tedious mapping; however, this is being replaced with terrestrial laser scanning technology. Laser scanning overcomes the problem of reaching high ceilings, providing new options to map underground landscapes with unprecedented level of detail and accuracy. The acquired point cloud can be handled conveniently with dedicated software, but applying traditional geomorphometry to analyse the cave surface is limited. This is because geomorphometry has been focused on parameterization and analysis of surficial terrain. The theoretical and methodological concept has been based on two-dimensional (2-D) scalar fields, which are sufficient for most cases of the surficial terrain. The terrain surface is modelled with a bivariate function of altitude (elevation) and represented by a raster digital elevation model. However, the cave is a 3-D entity; therefore, a different approach is required for geomorphometric analysis. In this paper, we demonstrate the benefits of high-resolution cave mapping and 3-D modelling to better understand the palaeohydrography of the Domica cave in Slovakia. This methodological approach adopted traditional geomorphometric methods in a unique manner and also new methods used in 3-D computer graphics, which can be applied to study other 3-D geomorphological forms.
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During the last decade, the need to survey and model caves or caverns in their correct three-dimensional geometry has increased due to two major competing motivations. One is the emergence of medium and long range terrestrial laser scanning (TLS) technology that can collect high point density with unprecedented accuracy and speed, and two, the expanding sphere of multidisciplinary research in understanding the origin and development of cave, called speleogenesis. Accurate surveying of caves has always been fundamental to understanding their origin and processes that lead to their current state and as well provide tools and information to predict future. Several laser scanning surveys have been carried out in many sophisticated cave sites around the world over the last decade for diverse applications; however, no comprehensive assessment of this development has been published to date. This paper reviews the state-of-the-art three-dimensional (3D) scanning in caves during the last decade. It examines a bibliography of almost fifty high quality works published in various international journals related to mapping caves in their true 3D geometry with focus on sensor design, methodology and data processing, and application development. The study shows that a universal standard method for 3D scanning has been established. The method provides flexible procedures that make it adaptable to suit different geometric conditions in caves. Significant progress has also been recorded in terms of physical design and technical capabilities. Over time, TLS devices have seen a reduction in size, and become more compact and lighter, with almost full panoramic coverage. Again, the speed, resolution, and measurement accuracy of scanners have improved tremendously, providing a wealth of information for the expanding sphere of emerging applications. Comparatively, point cloud processing packages are not left out of the development. They are more efficient in terms of handling large data volume and reduced processing time with advanced and more powerful functionalities to visualize and generate different products.
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The morphological knowledge of the territory, both in its surface and subterranean aspects, is the main premise to all decision-making procedures as well as all planning and management activities. Knowledge takes shape into reliable precise and complete thematic cartography and databases, which are necessary for anybody dealing with underground contexts: speleologists, scientists, public administrations, managing authorities etc. Surveys in caves are normally carried out with traditional techniques and instruments, which are essential for a first representation but not enough for a pragmatic effective topographic approach. Laser scanning technique can be an alternative to the traditional systems. Laser scanning quickly acquires the shape of cavities as "point clouds" (x, y, z coordinates and colour values) and produces a high precision database of the surveyed object. Laser scanning technology is therefore a feasible way to document caves in a precise exhaustive way, limiting risks relating to lack and/or inadequacy of data. The present paper explains the laser scanning survey carried out in San Giovanni mine near Iglesias (Sardinia, Italy), particularly in Santa Barbara and Santa Barbara 2 caves, the data post-processing and three-dimensional modelling of "point clouds" (operations performed with a dedicated software), and the use of the obtained digital model. Moreover, the paper describes the advantages of laser scanning for the hypogean survey in comparison to traditional methods and the future potentialities of a broad application of laser scanning instruments in caves.
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At the turn of the 20th century, the practical examination of caves went through a radical change. Governmental organizations and private clubs were founded in an attempt to establish speleology as an independent academic subject. In contrast to earlier cave visitors, travelers began entering underground areas and attributing the names of “explorers” or “researchers” to themselves. Fieldwork—especially cave surveying and cartography—became common practice in speleology and such work provided important clues on speleogenesis, which was a controversial issue in the first half of the 20th century. Due to the fact that speleologists began separating themselves from ordinary cave visitors and tourists, tools and instruments for cave exploration and mapping, such as carbide lamps, ropes, compasses, clinometers, and drawing boards, became the emblems of speleology. Through historical discourse analysis, this paper examines whether this change in the status and practice of underground fieldwork had an effect on the self-perception of speleology and led to new forms of social cooperation and control between speleologists. Further questions address the manner in which the usage of new surveying instruments and the relevance of cave mapping modified the scientific research parameters and the cultural perceptions of the subterranean world. As a contribution to speleo-history, this approach opens a new perspective on the social and cultural dimensions of speleological fieldwork as well as the historical, scientific, and political dynamics in which they were involved. Sources for this research comprised historical scientific papers on cave mapping, textbooks, and archive materials from the Austrian National Library, the Natural History Museum in Vienna, and the Austrian Speleological Association.
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Gaius Plinius Secundus, better known as Pliny the Elder, Roman naturalist and philosopher who lived between AD 23-79, described a particular and transparent stone known as Lapis Specularis, widely used in Roman times for the production of door and window panels. This particular stone similar to glass was quarried in many areas of the Roman Empire in Spain, Italy, Greece and North Africa from cavities or natural gorges, trying to follow the fractures in which this rock was formed. The stone is gypsum in its secondary macrocrystalline form that may be easily split to form thin transparent sheets. The first exploitation site for Lapis Specularis discovered in Italy is located in a cave called " Grotta della Lucerna ". This name derives from the discovery of some Roman lamps used by miners to lighten the cave during the mining operations. This paper describes the detailed laser scanner survey that we performed in this important archeological site.
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A third phase of investigation of the Peak Cavern Vestibule, using cutting-edge LIDAR total station equipment, obtained a 16.8 million co-ordinate data point cloud, which was re-sampled into a digitally-rendered, 3-D triangular surface model. Visualisation software allows dynamic viewing of the data model from any angle or orientation, with editing software allowing picking, interpretation and horizon generation of geological features of interest. Model analyses of surface 'en-echelon' joints reveal an anticlinal fold hinge mid-way through the Vestibule. Bedding planes were found to be sub-horizontal but parallel to the Vestibule main body axis.
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High resolution terrestrial laser scanning (TLS) within the Simud Hitam Cave, Gomantong, has proven successful at discriminating the nests of black-nest swiftlets from roosting bats in high, inaccessible locations. TLS data were imported into ArcGIS software, allowing for semi-automated counting of nests based on resolved geometry and laser return intensity. Nest resolution and counting accuracy was better than 2%. Spatial analysis of nest locations has established a maximum packing density of 268 nests/m2 in optimum locations, which correspond to roof slopes of >20 degrees. Co-occurring Rhinolophid bats roost adjacent to, but not within nest locations, preferring roof surfaces close to horizontal.
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Detailed geomorphological analysis has revealed that subhorizontal gypsum caves in the Northern Apennines (Italy) cut across bedding planes. These cave levels formed during cold periods with stable river beds, and are coeval with fluvial terraces of rivers that flow perpendicular to the strike of bedding in gypsum monoclines. When rivers entrench, renewed cave formation occurs very rapidly, resulting in the formation of a lower level. River aggradation causes cave alluviation and upward dissolution (paragenesis) in passages nearest to the river beds. The U-Th dating of calcite speleothems provides a minimum age for the formation of the cave passage in which they grew, which in turn provides age control on cave levels. The ages of all speleothems coincide with warmer and wetter periods when CO2 availability in the soils covering these gypsum areas was greater. This climate-driven speleogenetic model of epigenic gypsum caves in moderately to rapidly uplifting areas in temperate regions might be generally applicable to karst systems in different geological and climatic conditions.
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Currently there are many studies focused on the investigation of climatic and glaciological condition of ice caves. Here we present another way to address these studies, applying some methods already used in fields other than geomorphology. The versatility and accuracy provided by the use of modern topography and thermography techniques, using Terrestrial Laser Scanner and current thermographic cameras-and the creation of 3D thermographic models and orthothermographies derived from them - is shown to be a useful tool as it is difficult to obtain data from fieldwork and traditional methods used in caves. This paper presents the potential uses of combined TLS and thermographic techniques for monitoring some important climatological parameters in the sensitive periglacial environment of the Iberian Atlantic high mountains: Pena Castil Ice Cave (Picos de Europa, Northern Spain). A systematic application of such combined technologies to these kind of caves, is expected to contribute to a quantitative and concise characterization of the evolution of the ice as shown by the results of this study.
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The study of karst and its geomorphological structures is important for understanding the relationships between hydrology and climate over geological time. In that context, we conducted a terrestrial laser-scan survey to map geomorphological structures in the karst cave of Algar do Penico in southern Portugal. The point cloud data set obtained was used to generate 3D meshes with different levels of detail, allowing the limitations of mapping capabilities to be explored. In addition to cave mapping, the study focuses on 3D-mesh analysis, including the development of two algorithms for determination of stalactite extremities and contour lines, and on the interactive visualization of 3D meshes on the Web. Data processing and analysis were performed using freely available open-source software. For interactive visualization, we adopted a framework based on Web standards X3D, WebGL, and X3DOM. This solution gives both the general public and researchers access to 3D models and to additional data produced from map tools analyses through a web browser, without the need for plug-ins.
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We present the results of a study of the Vena del Gesso Basin (Romagna Apennines, Italy) integrating field analyses and analogue modelling. This basin represents one of the best-preserved top-thrust basins in the Northern Apennines foreland and is one of the few examples where primary evaporites, related to the Messinian salinity crisis of the Mediterranean, widely crop out. The structural style affecting the Messinian gypsum is examined to get insights into the mechanism responsible for the overall deformation features recognizable in the area. The evaporites are completely detached at the base and widespread back-thrusts, repeatedly doubling these deposits, strongly contrast with the regional forelandward vergence of structures in the Apennines. On the basis of the comparison between field data and experimental results, the features characterising this area can be described as the result of the deformation linked to the sequential activation of an obliquely propagating passive-roof duplex. Analogue models evidenced the major role played (1) by syntectonic erosion that promoted the development of passive-roof duplex style, as well as (2) the role of décollement level pinch-out that determined an oblique progression of deformation. Finally our data lead to reconsider the palaeoenvironmental reconstruction concerning the onset of the Messinian salinity crisis in the Mediterranean. Copyright © 2007 John Wiley & Sons, Ltd.
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