Integrating UAS Photogrammetry and Digital Image Correlation for Monitoring of Large Landslides

Abstract

This paper shows the results of applying high-resolution Unmanned Aircraft System (UAS) photogrammetric surveying on a large landslide. A real case study, where permanently installing GCPs could be complex, where natural shaped and formed land pose severe limitations in deploying ground targets with optimal geometric configuration. We analysed performances in terms of survey accuracy obtained by performing photogrammetric surveys through the Zenmuse P1 DJI optical camera and Phantom 4 Pro 2. In combination with DJI Matrice 300 UAS, the P1 camera allows direct georeferencing through GNSS observations in RTK mode. Photogrammetric surveys, performed through different georeferencing methods, have been compared. Several targets have been permanently installed on the ground over the maximum vegetation height to guarantee long-lasting reference over the years in the area, which is characterised by a diffuse short vegetation coverage. Multitemporal UAS surveys have been then compared using Digital Image Correlation (DIC) algorithms, and deformation maps have been produced. Afterwards, DIC results were compared with observations made by the GNSS ground-based permanent receivers resulting in a standard deviation of 0,077 m. Through results analysis, good accordance between ground-based GNSS observations and DIC analysis on the photogrammetric surveys have been identified for the same time span. To conclude, this type of landslide presents a moderate deformation speed; in such a case, effective deformations monitoring could be achieved using pseudo-direct georeferencing, which permitted a 0.24 m accuracy on the whole tested area.

Rapid Assessment of Landslide Dynamics by UAV-RTK Repeated Surveys Using Ground Targets: The Ca’ Lita Landslide (Northern Apennines, Italy)

“…Moreover, looking at the flanks of the landslide's body (Figure 9B,C), although numerous fractures are visible, one main surface of rupture can be traced along all the transect, thus confirming the combination of The overall distribution of displacements along the investigated transect can be compared to that of a viscous liquid channelized in the track zone that, as previously said, together with areas of significant internal deformation (Figure 9A), constitutes a fundamental characteristic of earthflows. Moreover, looking at the flanks of the landslide's body (Figure 9B,C), although numerous fractures are visible, one main surface of rupture can be traced along all the transect, thus confirming the combination of earthflow and earthslide types of movement that was already proposed in previous works [53,54,66]. earthflow and earthslide types of movement that was already proposed in previous works [53,54,66].…”

“…Moreover, looking at the flanks of the landslide's body (Figure 9B,C), although numerous fractures are visible, one main surface of rupture can be traced along all the transect, thus confirming the combination of earthflow and earthslide types of movement that was already proposed in previous works [53,54,66]. earthflow and earthslide types of movement that was already proposed in previous works [53,54,66].…”

Multitemporal Analysis of Slow-Moving Landslides and Channel Dynamics through Integrated Remote Sensing and In Situ Techniques

“…DEMs can be compared in GIS software and the cell-by-cell height difference calculated, leading to vertical displacement analyses and volume calculations [58,[67][68][69]. Orthomosaics can be processed with feature tracking algorithms in order to compute the planar movements of specific features [70,71]. Additionally, 3D point clouds can be compared and the pointto-point distance between subsequent 3D reconstructions computed [72][73][74] to evaluate 3D displacements.…”

UAV Photogrammetry for Soil Surface Deformation Detection in a Timber Harvesting Area, South Korea

“…Despite their high-precision 3D resolution, conducting UAV systems requires site preparation for field reference. Many studies have used ground control points (GCPs) at distinctive objects for reference and measured the coordinates of the corresponding GCPs using a global navigation satellite system (GNSS) [18,29,30]. Surveys from field operations and UAVs using 3D data, such as point cloud data (PCD), were then acquired with the support of the structure from motion (SfM) algorithm.…”