Assessing the Accuracy of High Resolution Digital Surface Models Computed by PhotoScan® and MicMac® in Sub-Optimal Survey Conditions

Abstract

Abstract:For monitoring purposes and in the context of geomorphological research, Unmanned Aerial Vehicles (UAV) appear to be a promising solution to provide multi-temporal Digital Surface Models (DSMs) and orthophotographs. There are a variety of photogrammetric software tools available for UAV-based data. The objective of this study is to investigate the level of accuracy that can be achieved using two of these software tools: Agisoft PhotoScan ® Pro and an open-source alternative, IGN © MicMac ® , in sub-optimal survey conditions (rugged terrain, with a large variety of morphological features covering a range of roughness sizes, poor GPS reception). A set of UAV images has been taken by a hexacopter drone above the Rivière des Remparts, a river on Reunion Island. This site was chosen for its challenging survey conditions: the topography of the study area (i) involved constraints on the flight plan; (ii) implied errors on some GPS measurements; (iii) prevented an optimal distribution of the Ground Control Points (GCPs) and; (iv) was very complex to reconstruct. Several image processing tests are performed with different scenarios in order to analyze the sensitivity of each software package to different parameters (image quality, numbers of GCPs, etc.). When computing the horizontal and vertical errors within a control region on a set of ground reference targets, both methods provide rather similar results. A precision up to 3-4 cm is achievable with these software packages. The DSM quality is also assessed over the entire study area comparing PhotoScan DSM and MicMac DSM with a Terrestrial Laser Scanner (TLS) point cloud. PhotoScan and MicMac DSM are also compared at the scale of particular features. Both software packages provide satisfying results: PhotoScan is more straightforward to use but its source code is not open; MicMac is recommended for experimented users as it is more flexible.

Study on 3D Point Clouds Accuracy of Elongated Object Reconstruction in Close Range – Comparison of Different Software

“…The performed measurements and advanced digital processing workflow of the block of photos used for the test are presented in Figure 3. Point clouds generation using the tested software Automatic determination of interior orientation elements (IO) for the DSLR Nikon D5100 camera, the elements of the spatial orientation (EO) of photos and generation of the dense point cloud were performed using four applications: − Agisoft Photoscan v. 1.2.6 (commercial license) -Agisoft LLC (Jaud et al 2016;Niederheiser et al 2016;Remondino et al 2014).…”

Open Source and Independent Methods for Bundle Adjustment Assessment in Close-Range UAV Photogrammetry

“…Open source solutions are often used to perform the comparison, as they provide a more open algorithm, which the users may parametrize to match their needs. Apero in particular has been used for such comparisons in previous research [23][24][25]. Other papers focus on optimizing PhotoScan processing [26] and assessing the results of PhotoScan projects in terms of computed covariances of both internal and external parameters [27], similar to DBAT's functionality.…”

High Resolution Historical Topography: Getting More from Archival Aerial Photographs

“…Both proprietary and open source photogrammetric software applications exist, which are used for work and research [6][7][8]. Unlike proprietary software, however, open source gives the possibility to examine [9,10], modify and redistribute the algorithms, and is particularly suitable for research reproducibility and replicability [11] and closer to the general concept of open science [12].…”