Surface roughness of rock faces through the curvature of triangulated meshes

Lai, Po Kong; Samson, C.; Bose, Prosenjit

doi:10.1016/j.cageo.2014.05.010

Cited by 29 publications

(19 citation statements)

References 27 publications

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“…As a result, generally convex features, such as stalactites, stalagmites, or pendants, have positive mean curvature values while concave features, such as sinks, cavities, half tubes, or sinks have negative values. Lai et al (2014) used the curvature of a 3-D mesh as a measure of the surface roughness of rock faces.…”

Section: Analysing the Cave Surface Using 3-d Geomorphometrymentioning

confidence: 99%

Geomorphometric analysis of cave ceiling channels mapped with 3-D terrestrial laser scanning

Gallay

Hochmuth

Kaňuk

et al. 2016

Hydrol. Earth Syst. Sci.

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Abstract. 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 twodimensional (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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Section: Analysing the Cave Surface Using 3-d Geomorphometrymentioning

confidence: 99%

Geomorphometric analysis of cave ceiling channels mapped with 3-D terrestrial laser scanning

Gallay

Hochmuth

Kaňuk

et al. 2016

Hydrol. Earth Syst. Sci.

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“…In the past few decades, a range of microtopographic data collection methods have been used in rock breakdown and soil erosion studies. These include (1) laser scanning techniques (Fardin et al, 2001(Fardin et al, , 2004Bourke et al, 2007;Bourke et al, 2008;Aguilar et al, 2009;Sturzenegger and Stead, 2009;MŁynarczuk, 2010;Medapati et al, 2013;Chen et al, 2014;Ge et al, 2014;Lai et al, 2014), (2) stereophotogrammetry (Rieke-Zapp and Nearing, 2005;Taconet and Ciarletti, 2007;Aguilar et al, 2009;Bui et al, 2009;Sturzenegger and Stead, 2009;Kim et al, 2015), and (3) micro-roughness meters (MRMs) (McCarroll, 1992;Mc-Carroll and Nesje, 1996;White et al, 1998). However, there are significant logistical, technical, and, for some, financial constraints that have hindered the adoption of these methods, particularly in physically challenging terrains such as remote, difficult to access, and steep terrains.…”

Section: Introductionmentioning

confidence: 99%

“…While the resolution, precision, and accuracy of MRM (∼ 0.001 to 0.005 mm) is higher than laser scanning and photogrammetry techniques (sub-millimetre to millimetre), the topographic data obtained from MRM are two-dimensional and limit the analysis to the calculation of profile roughness parameters. The profile roughness parameters only provide information along a profile, not the entire rock surface, which often makes it difficult to determine the exact nature of a topographic feature (Leach, 2013). In comparison, 3-D data from laser scanners and photogrammetry enable the calculation of areal surface roughness parameters.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A method based on structure-from-motion photogrammetry to generate sub-millimetre-resolution digital elevation models for investigating rock breakdown features

Verma

Bourke

2019

Earth Surf. Dynam.

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Abstract. We have generated sub-millimetre-resolution DEMs of weathered rock surfaces using SfM photogrammetry techniques. We apply a close-range method based on structure-from-motion (SfM) photogrammetry in the field and use it to generate high-resolution topographic data for weathered boulders and bedrock. The method was pilot tested on extensively weathered Triassic Moenkopi sandstone outcrops near Meteor Crater in Arizona. Images were taken in the field using a consumer-grade DSLR camera and were processed in commercially available software to build dense point clouds. The point clouds were registered to a local 3-D coordinate system (x, y, z), which was developed using a specially designed triangle-coded control target and then exported as digital elevation models (DEMs). The accuracy of the DEMs was validated under controlled experimental conditions. A number of checkpoints were used to calculate errors. We also evaluated the effects of image and camera parameters on the accuracy of our DEMs. We report a horizontal error of 0.5 mm and vertical error of 0.3 mm in our experiments. Our approach provides a low-cost method for obtaining very high-resolution topographic data on weathered rock surfaces (area < 10 m2). The results from our case study confirm the efficacy of the method at this scale and show that the data acquisition equipment is sufficiently robust and portable. This is particularly important for field conditions in remote locations or steep terrain where portable and efficient methods are required.

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“…Animal-scale 3D environmental models collected from free-ranging individuals have great potential to be used in the measurement of ground inclination, obstacle detection, and derivation of various surface roughness or traversability indexes (e.g. [53][54][55]). Such variables could then be examined in relation to accelerometer-derived proxies of energy expenditure to further our understanding of the 'energetic envelope' [51] within which an animal may optimise its behavioural patterns.…”

Section: Discussionmentioning

confidence: 99%

Joining the dots: reconstructing 3D environments and movement paths using animal-borne devices

McClune

2018

Anim Biotelemetry

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Background: Animal-attached sensors are increasingly used to provide insights on behaviour and physiology. However, such tags usually lack information on the structure of the surrounding environment from the perspective of a study animal and thus may be unable to identify potentially important drivers of behaviour. Recent advances in robotics and computer vision have led to the availability of integrated depth-sensing and motion-tracking mobile devices. These enable the construction of detailed 3D models of an environment within which motion can be tracked without reliance on GPS. The potential of such techniques has yet to be explored in the field of animal biotelemetry. This report trials an animal-attached structured light depth-sensing and visual-inertial odometry motion-tracking device in an outdoor environment (coniferous forest) using the domestic dog (Canis familiaris) as a compliant test species.Results: A 3D model of the forest environment surrounding the subject animal was successfully constructed using point clouds. The forest floor was labelled using a progressive morphological filter. Trees trunks were modelled as cylinders and identified by random sample consensus. The predicted and actual presence of trees matched closely, with an object-level accuracy of 93.3%. Individual points were labelled as belonging to tree trunks with a precision, recall, and F β score of 1.00, 0.88, and 0.93, respectively. In addition, ground-truth tree trunk radius measurements were not significantly different from random sample consensus model coefficient-derived values. A first-person view of the 3D model was created, illustrating the coupling of both animal movement and environment reconstruction. Conclusions:Using data collected from an animal-borne device, the present study demonstrates how terrain and objects (in this case, tree trunks) surrounding a subject can be identified by model segmentation. The device pose (position and orientation) also enabled recreation of the animal's movement path within the 3D model. Although some challenges such as device form factor, validation in a wider range of environments, and direct sunlight interference remain before routine field deployment can take place, animal-borne depth sensing and visual-inertial odometry have great potential as visual biologging techniques to provide new insights on how terrestrial animals interact with their environments.

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Surface roughness of rock faces through the curvature of triangulated meshes

Cited by 29 publications

References 27 publications

Geomorphometric analysis of cave ceiling channels mapped with 3-D terrestrial laser scanning

Geomorphometric analysis of cave ceiling channels mapped with 3-D terrestrial laser scanning

A method based on structure-from-motion photogrammetry to generate sub-millimetre-resolution digital elevation models for investigating rock breakdown features

Joining the dots: reconstructing 3D environments and movement paths using animal-borne devices

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