Cross-Polarized SfM Photogrammetry for the Spatial Reconstruction of Challenging Surfaces, the Case Study of Dobšiná Ice Cave (Slovakia)

Bartoš, Karol; Pukanská, Katarína; Kseňak, Ľubomír; Gašinec, Juraj; Bella, Pavel

doi:10.3390/rs15184481

Cited by 6 publications

(2 citation statements)

References 43 publications

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“…This allows for the consideration of historic building elements as topographic surfaces in which analytical measurements of material properties can be represented and managed as "geographical" data within a GIS. This includes combining measurements, carrying out data operations, and even integrating multispectral imagery [9,17,18].…”

Section: Introductionmentioning

confidence: 99%

Characterization of Anisotropic Salt Weathering through Nondestructive Techniques Mapping Using a GIS Environment

Gomez-Heras,

López-González,

Gil-Muñoz

et al. 2024

Sensors

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Doctrinal texts on architectural heritage conservation emphasize the importance of fully understanding the structural and material characteristics and utilizing information systems. Photogrammetry allows for the generation of detailed, geo-referenced Digital Elevation Models of architectural elements at a low cost, while GIS software enables the addition of layers of material characteristic data to these models, creating different property maps that can be combined through map algebra. This paper presents the results of the mechanical characterization of materials and salt-related decay forms of the polygonal apse of the 13th-century monastery of Santa María de Bonaval (Guadalajara, Spain), which is primarily affected by salt crystallization. Rock strength is estimated using on-site nondestructive testing (ultrasound pulse velocity and Leeb hardness). They are mapped and combined through map algebra to derive a single mechanical soundness index (MSI) to determine whether the decay of the walls could be dependent on the orientation. The presented results show that salt decay in the building is anisotropic, with the south-facing side of the apse displaying an overall lower MSI than the others. The relative overheating of the south-facing side of the apse enhances the effect of salt crystallization, thereby promoting phase transitions between epsomite and hexahydrite.

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Section: Introductionmentioning

confidence: 99%

Characterization of Anisotropic Salt Weathering through Nondestructive Techniques Mapping Using a GIS Environment

Gomez-Heras,

López-González,

Gil-Muñoz

et al. 2024

Sensors

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show abstract

“…Three-dimensional laser scanning can be performed from stationary terrestrial [2] as well as mobile [3] and, recently, unmanned aerial vehicle (UAV) platforms [4][5][6] or airplanes [7,8]. The situation is similar in photogrammetry-terrestrial photogrammetry [9] as well as airborne photogrammetry are commonly used [10], with UAV photogrammetry being on the rise in recent years. The latter method is easy to use, and the equipment acquisition costs are relatively low.…”

Section: Introductionmentioning

confidence: 99%

Color-Based Point Cloud Classification Using a Novel Gaussian Mixed Modeling-Based Approach versus a Deep Neural Network

Štroner,

Urban,

Línková

2023

Remote Sensing

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The classification of point clouds is an important research topic due to the increasing speed, accuracy, and detail of their acquisition. Classification using only color is basically absent in the literature; the few available papers provide only algorithms with limited usefulness (transformation of three-dimensional color information to a one-dimensional one, such as intensity or vegetation indices). Here, we proposed two methods for classifying point clouds in RGB space (without using spatial information) and evaluated the classification success since it allows a computationally undemanding classification potentially applicable to a wide range of scenes. The first is based on Gaussian mixture modeling, modified to exploit specific properties of the RGB space (a finite number of integer combinations, with these combinations repeated in the same class) to automatically determine the number of spatial normal distributions needed to describe a class (mGMM). The other method is based on a deep neural network (DNN), for which different configurations (number of hidden layers and number of neurons in the layers) and different numbers of training subsets were tested. Real measured data from three sites with different numbers of classified classes and different “complexity” of classification in terms of color distinctiveness were used for testing. Classification success rates averaged 99.0% (accuracy) and 96.2% (balanced accuracy) for the mGMM method and averaged 97.3% and 96.7% (balanced accuracy) for the DNN method in terms of the best parameter combinations identified.

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Effects of Analog Modeling Materials on Topographic Photogrammetry (SfM) Reconstructions

Cawood,

Wyrick

2024

Earth and Space Science

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Accurate topographic data are essential for quantitative structural analysis, both in natural settings and in the laboratory. The selection of modeling materials (with appropriate rheological properties) is known to be fundamental for the success of scaled physical analog experiments. However, the optical properties of analog materials and their impact on the reliability and precision of high‐resolution topographic reconstructions have not (to our knowledge) previously been assessed. Here we evaluate the effects of material composition, color, and grain size on Structure‐from‐Motion (SfM) photogrammetry reconstruction efficacy for deformed and undeformed model configurations in the laboratory. Image collections for photogrammetry are acquired from multiple camera positions with a handheld digital camera, and reconstructions are registered using ground control points in a local coordinate system. Static experiments show that low reflectivity granular materials (e.g., silica sand, volcanic ash, pumice, and Al2O3) yield relatively reliable photogrammetry data for a wide range of grain sizes (44–2,400 μm) but larger grain sizes (≥250 μm) provide more robust results. Reflective materials (e.g., glass beads, wet clay) yield less reliable point‐clouds but the addition of low‐reflectivity granular materials (e.g., Al2O3 grains) on the surface of wet clay improves reconstruction results, with higher grain densities typically yielding lower point‐cloud residuals. SfM‐photogrammetry reconstruction of deformed clay analog models tends to improve at higher extension magnitudes because of fault and associated texture development on model surfaces. We anticipate that our results will help practitioners to improve the precision and reliability of photogrammetric data acquired in the analog modeling laboratory.

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Cross-Polarized SfM Photogrammetry for the Spatial Reconstruction of Challenging Surfaces, the Case Study of Dobšiná Ice Cave (Slovakia)

Cited by 6 publications

References 43 publications

Characterization of Anisotropic Salt Weathering through Nondestructive Techniques Mapping Using a GIS Environment

Characterization of Anisotropic Salt Weathering through Nondestructive Techniques Mapping Using a GIS Environment

Color-Based Point Cloud Classification Using a Novel Gaussian Mixed Modeling-Based Approach versus a Deep Neural Network

Effects of Analog Modeling Materials on Topographic Photogrammetry (SfM) Reconstructions

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