Applied Sciences

Research

27 pages, 14070 KiB

Open AccessArticle

Integrating Virtual Reality and GIS Tools for Geological Mapping, Data Collection and Analysis: An Example from the Metaxa Mine, Santorini (Greece)

by Varvara Antoniou, Fabio Luca Bonali, Paraskevi Nomikou, Alessandro Tibaldi, Paraskevas Melissinos, Federico Pasquaré Mariotto, Fabio Roberto Vitello, Mel Krokos and Malcolm Whitworth

Appl. Sci. 2020, 10(23), 8317; https://doi.org/10.3390/app10238317 - 24 Nov 2020

Cited by 20 | Viewed by 4751

Abstract

In the present work we highlight the effectiveness of integrating different techniques and tools for better surveying, mapping and collecting data in volcanic areas. We use an Immersive Virtual Reality (IVR) approach for data collection, integrated with Geographic Information System (GIS) analysis in [...] Read more.

In the present work we highlight the effectiveness of integrating different techniques and tools for better surveying, mapping and collecting data in volcanic areas. We use an Immersive Virtual Reality (IVR) approach for data collection, integrated with Geographic Information System (GIS) analysis in a well-known volcanological site in Santorini (Metaxa mine), a site where volcanic processes influenced the island’s industrial development, especially with regard to pumice mining. Specifically, we have focused on: (i) three-dimensional (3D) high-resolution IVR scenario building, based on Structure from Motion photogrammetry (SfM) modeling; (ii) subsequent geological survey, mapping and data collection using IVR; (iii) data analysis, e.g., calculation of extracted volumes, as well as production of new maps in a GIS environment using input data directly from the IVR survey; and finally, (iv) presentation of new outcomes that highlight the importance of the Metaxa Mine as a key geological and volcanological geosite. Full article

(This article belongs to the Special Issue 3D Reconstruction and Data Analysis: Cutting-Edge Techniques for Terrestrial and Marine Environments)

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21 pages, 8994 KiB

Open AccessArticle

The VIRTUALDiver Project. Making Greece’s Underwater Cultural Heritage Accessible to the Public

by George Pehlivanides, Kostas Monastiridis, Alexandros Tourtas, Elli Karyati, Giotis Ioannidis, Konstantina Bejelou, Varvara Antoniou and Paraskevi Nomikou

Appl. Sci. 2020, 10(22), 8172; https://doi.org/10.3390/app10228172 - 18 Nov 2020

Cited by 17 | Viewed by 4544

Abstract

Reaching the underwater world is undoubtedly an incomparable adventure. Impressive geological structures, flourishing ecosystems, shipwrecks, and submerged landscapes lie beneath the sea surface in wait for discovery. However, this world is accessible only to those who have the chance to dive or to [...] Read more.

Reaching the underwater world is undoubtedly an incomparable adventure. Impressive geological structures, flourishing ecosystems, shipwrecks, and submerged landscapes lie beneath the sea surface in wait for discovery. However, this world is accessible only to those who have the chance to dive or to scientists conducting underwater research. By means of a dynamically developing sector of informatics utilizing Virtual (VR) and Augmented Reality (AR) practices, the VIRTUALDiver project intends to provide access to all the aforementioned hidden “treasures” through the creation of an innovative platform providing unique interactive experiences. More specifically, specialized guided tours in natural and virtual environments covering areas of touristic, cultural, and environmental interest. VIRTUALDiver is an experience, design and content presentation platform, a custom-made add-on environment within the Unity 3D authoring tool, offering the ability to manage multimedia content in a simplified way. No specialized programming knowledge is required, enabling the project’s interdisciplinary consortium to easily collaborate and exchange ideas. The expected result is the establishment of a successful educational and entertaining cultural product to support businesses and professionals operating in the field of culture-tourism. Above all, VIRTUALDiver aspires to become a novel form of storytelling, immersing the user into unique experiences under the waves. Full article

(This article belongs to the Special Issue 3D Reconstruction and Data Analysis: Cutting-Edge Techniques for Terrestrial and Marine Environments)

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24 pages, 10071 KiB

Open AccessArticle

Reconstruction of Late Pleistocene-Holocene Deformation through Massive Data Collection at Krafla Rift (NE Iceland) Owing to Drone-Based Structure-from-Motion Photogrammetry

by Fabio Luca Bonali, Alessandro Tibaldi, Noemi Corti, Luca Fallati and Elena Russo

Appl. Sci. 2020, 10(19), 6759; https://doi.org/10.3390/app10196759 - 27 Sep 2020

Cited by 8 | Viewed by 3223

Abstract

In the present work, we demonstrate how drone surveys coupled with structure-from-motion (SfM) photogrammetry can help to collect huge amounts of very detailed data even in rough terrains where logistics can affect classical field surveys. The area of study is located in the [...] Read more.

In the present work, we demonstrate how drone surveys coupled with structure-from-motion (SfM) photogrammetry can help to collect huge amounts of very detailed data even in rough terrains where logistics can affect classical field surveys. The area of study is located in the NW part of the Krafla Fissure Swarm (NE Iceland), a volcanotectonic rift composed of eruptive centres, extension fractures, and normal faults. The surveyed sector is characterized by the presence of a hyaloclastite ridge composed of deposits dated, on a stratigraphic basis, to the Weichselian High Glacial (29.1–12.1 ka BP), and a series of lava flows mostly dating back to 11–12 ka BP. The integration of remotely sensed surveys and field inspections enabled us to recognize that this segment of the Krafla rift is made of grabens arranged en-échelon with a left-stepping geometry. A major graben increases in width in correspondence of the hyaloclastite cone; we interpret this geometry as resulting from the mechanical contrast between the stiffer lava succession and the softer hyaloclastites, which favours the development of concentric faults. We also measured a total extension of 16.6 m and 11.2 m along the fractures affecting the lava units, and a total extension in the hyaloclastites of 29.3 m. This produces an extension rate of 1.4 mm/yr in the Holocene lavas and 1.7 ± 0.7 mm/yr in the Weichselian hyaloclastite deposits. The spreading direction we obtained for this area is N97.7° E, resulting from the av. of 568 opening direction values. Full article

(This article belongs to the Special Issue 3D Reconstruction and Data Analysis: Cutting-Edge Techniques for Terrestrial and Marine Environments)

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28 pages, 8128 KiB

Open AccessArticle

Digital Field Mapping and Drone-Aided Survey for Structural Geological Data Collection and Seismic Hazard Assessment: Case of the 2016 Central Italy Earthquakes

by Daniele Cirillo

Appl. Sci. 2020, 10(15), 5233; https://doi.org/10.3390/app10155233 - 29 Jul 2020

Cited by 26 | Viewed by 4891

Abstract

In this work, a high-resolution survey of the coseismic ground ruptures due to the 2016 Central Italy seismic sequence, performed through a dedicated software installed on a digital device, is strengthened by the analysis of a set of drone-acquired images. We applied this [...] Read more.

In this work, a high-resolution survey of the coseismic ground ruptures due to the 2016 Central Italy seismic sequence, performed through a dedicated software installed on a digital device, is strengthened by the analysis of a set of drone-acquired images. We applied this integrated approach to two active sections of the Mt Vettore active fault segment which, in the Castelluccio di Norcia plain (central Italy), were affected by surface faulting after the most energetic events of the sequence: the 24 August, Mw 6.0, Amatrice and 30 October, Mw 6.5, Norcia earthquakes. The main aim is to establish the range in which the results obtained measuring the same structures using different tools vary. An operating procedure, which can be helpful to map extensive sets of coseismic ground ruptures especially where the latter affects wide, poorly accessible, or dangerous areas, is also proposed. We compared datasets collected through different technologies, including faults attitude, dip-angles, coseismic displacements, and slip vectors. After assessing the accuracy of the results, even at centimetric resolutions, we conclude that the structural dataset obtained through remote sensing techniques shows a high degree of reliability. Full article

(This article belongs to the Special Issue 3D Reconstruction and Data Analysis: Cutting-Edge Techniques for Terrestrial and Marine Environments)

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35 pages, 4924 KiB

Open AccessArticle

OpenMP Implementation of a Novel Potential-Field-Data Source-Growth-Based Inversion Approach for 3D Salt Imaging in Deepwater Gulf of Mexico

by Naín Vera, Carlos Couder-Castañeda, Jorge Hernández, Alfredo Trujillo-Alcántara, Mauricio Orozco-del-Castillo and Carlos Ortiz-Aleman

Appl. Sci. 2020, 10(14), 4798; https://doi.org/10.3390/app10144798 - 13 Jul 2020

Cited by 1 | Viewed by 2156

Abstract

Potential-field-data imaging of complex geological features in deepwater salt-tectonic regions in the Gulf of Mexico remains an open active research field. There is still a lack of resolution in seismic imaging methods below and in the surroundings of allochthonous salt bodies. In this [...] Read more.

Potential-field-data imaging of complex geological features in deepwater salt-tectonic regions in the Gulf of Mexico remains an open active research field. There is still a lack of resolution in seismic imaging methods below and in the surroundings of allochthonous salt bodies. In this work, we present a novel three-dimensional potential-field-data simultaneous inversion method for imaging of salt features. This new approach incorporates a growth algorithm for source estimation, which progressively recovers geological structures by exploring a constrained parameter space; restrictions are posed from a priori geological knowledge of the study area. The algorithm is tested with synthetic data corresponding to a real complex salt-tectonic geological setting commonly found in exploration areas of deepwater Gulf of Mexico. Due to the huge amount of data involved in three-dimensional inversion of potential field data, the use of parallel computing techniques becomes mandatory. In this sense, to alleviate computational burden, an easy to implement parallelization strategy for the inversion scheme through OpenMP directives is presented. The methodology was applied to invert and integrate gravity, magnetic and full tensor gradient data of the study area. Full article

(This article belongs to the Special Issue 3D Reconstruction and Data Analysis: Cutting-Edge Techniques for Terrestrial and Marine Environments)

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19 pages, 7917 KiB

Open AccessArticle

Surveying and High-Resolution Topography of the Ochtiná Aragonite Cave Based on TLS and Digital Photogrammetry

by Katarína Pukanská, Karol Bartoš, Pavel Bella, Juraj Gašinec, Peter Blistan and Ľudovít Kovanič

Appl. Sci. 2020, 10(13), 4633; https://doi.org/10.3390/app10134633 - 4 Jul 2020

Cited by 27 | Viewed by 4130

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue 3D Reconstruction and Data Analysis: Cutting-Edge Techniques for Terrestrial and Marine Environments)

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18 pages, 3102 KiB

Open AccessFeature PaperArticle

Evidence of Hierarchy in the Drainage Basins Size Distribution of Greece Derived from ASTER GDEM-v2 Data

by Filippos Vallianatos and Maria Kouli

Appl. Sci. 2020, 10(1), 248; https://doi.org/10.3390/app10010248 - 28 Dec 2019

Cited by 1 | Viewed by 2464

Abstract

The drainage basins of Greece are analyzed in terms of hierarchy and discussed in view of Tsallis Entropy. This concept has been successfully used in a variety of complex systems, where fractality, memory and long-range interactions are dominant. The analysis indicates that the [...] Read more.

The drainage basins of Greece are analyzed in terms of hierarchy and discussed in view of Tsallis Entropy. This concept has been successfully used in a variety of complex systems, where fractality, memory and long-range interactions are dominant. The analysis indicates that the statistical distribution of drainage basins’ area in Greece, presents a hierarchical pattern that can be viewed within the frame of non-extensive statistical physics. Our work was based on the analysis of the ASTER GDEM v2 Digital Elevation Model of Greece, which offers a 30 m resolution, creating an accurate drainage basins’ database. Analyzing the drainage size (e.g., drainage basin area)-frequency distribution we discuss the connection of the observed power law exponents with the Tsallis entropic parameters, demonstrating the hierarchy observed in drainage areas for the set created for all over Greece and the subsets of drainages in the internal and external Hellenides that are the main tectonic structures in Greece. Furthermore, we discuss in terms of Tsallis entropy, the hierarchical patterns observed when the drainages are classified according to their relief or the Topographic Position Index (TPI). The deviation of distribution from power law for large drainages area is discussed. Full article

(This article belongs to the Special Issue 3D Reconstruction and Data Analysis: Cutting-Edge Techniques for Terrestrial and Marine Environments)

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17 pages, 6661 KiB

Open AccessArticle

Retrieval of Nearshore Bathymetry around Ganquan Island from LiDAR Waveform and QuickBird Image

by Zhen Zhang, Jingyu Zhang, Yi Ma, Huibo Tian and Tao Jiang

Appl. Sci. 2019, 9(20), 4375; https://doi.org/10.3390/app9204375 - 16 Oct 2019

Cited by 8 | Viewed by 2395

Abstract

Optical remote sensing is an effective means of water depth measurement, but the current approach of mainstream bathymetric retrieval requires a large amount of onsite measurement data. Such data are hard to obtain from places where underwater terrains are complicated and unsteady, and [...] Read more.

Optical remote sensing is an effective means of water depth measurement, but the current approach of mainstream bathymetric retrieval requires a large amount of onsite measurement data. Such data are hard to obtain from places where underwater terrains are complicated and unsteady, and from sea areas affected by issues with rights and conflicts of interest. In recent years, the emergence of airborne light detection and ranging (LiDAR) provided a new technical means for field bathymetric survey. In this study, water depth inversion was carried out around an island far from the mainland by using remote sensing images and real LiDAR waveform data. Multi-Gaussian function fitting was proposed to extract water depth data from waveform data, and bathymetric values were used as control and validation data of the active and passive combination of water depth inversion. Results show that the relative error was 5.6% for the bathymetric retrieval from LiDAR waveform data, and the accuracy meets the requirements of ocean bathymetry. The average relative error of water depth inversion based on active and passive remote sensing was less than 9%. The method used in this study can also reduce the use of LiDAR data and the cost, thus providing a new idea for future coastal engineering application and construction. Full article

(This article belongs to the Special Issue 3D Reconstruction and Data Analysis: Cutting-Edge Techniques for Terrestrial and Marine Environments)

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