De Cock, Laure

De Maeyer, Philippe

De Wit, Bart

Delaloye, Reynald

Frankl, Amaury

Hendrickx, Hanne

Lambiel, Christophe

Nyssen, Jan

Vivero, Sebastián

Ghent University Academic Bibliography

Geophysical Research AbstractsVol. 21, EGU2019-2280, 2019EGU General Assembly 2019© Author(s) 2018. CC Attribution 4.0 license.Investigating software variation in creating detailed Digital SurfaceModels: Agisoft Photoscan applied on a high-alpine rock glacierReynald Delaloye (1), Hanne Hendrickx (2), Sebastián Vivero (3), Bart De Wit (2), Christophe Lambiel (3),Laure De Cock (2), Philippe De Maeyer (2), Jan Nyssen (2), Amaury Frankl (2,4)(1) Department of Geosciences, Fribourg University, Switzerland, (2) Department of Geography, Ghent University, Belgium,(3) Institute of Earth Surface Dynamics, University of Lausanne, Lausanne, Switzerland, (4) Postdoctoral Fellow of theResearch Foundation Flanders (FWO)Agisoft PhotoScan is a commonly used software to produce Digital Surface Models (DSMs) in geoscientific re-search. Based on the Structure-from-Motion (SfM) and Multi-View Stereo (MVS) principles, the software pro-duces 3D environments from 2D imagery (often taken by Unmanned Aerial Vehicles (UAV)). However, randomelements in the unpublished computer-vision algorithms used, can cause variation in the model outputs. To the bestof our knowledge, the reproducibility of PhotoScan is not yet explicitly addressed by earlier research. However,it is known that the software processing algorithms directly influence model accuracy. Therefore, we explored thereproducibility of a 3D model of a complex alpine environment from multiple PhotoScan runs. This is done withexactly the same images, processing settings and Ground Control Points (GCPs) as these input parameters havebeen identified influencing accuracies by previous research. This way, ten model runs were performed on UAVimagery of a rock glacier to analyse the magnitude of the variation between the different model outputs. This vari-ation was quantified calculating the standard deviation of each cell value in the respective DSMs and derivatives(curvature). Places with steep slope gradients have considerably more DSM variation (up to 10 cm) but stay withinthe range of the model’s accuracy (10 vertical cm) for 88 – 96% of the area. The edges of the model also show alarger variability (0.10 – 3 m), related to a lower number of overlapping images. These results should be accountedfor when performing a geomorphological research at centimetre scale using PhotoScan, especially in areas with acomplex relief. We found that using medium-quality runs, additional oblique viewpoints and respecting a minimumof five overlapping images can minimize the software’s variations.

Investigating software variation in creating detailed Digital Surface Models : Agisoft Photoscan applied on a high-alpine rock glacier

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Investigating software variation in creating detailed Digital Surface Models : Agisoft Photoscan applied on a high-alpine rock glacier

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