Morphological Mapping of 13 August 2017 Kotropi Landslide using Images
and Videos from Drone and Structure from Motion
Landslides exhibit complex geomorphological features, which are
difficult to monitor and map the changes. Photogrammetric methods have
emerged as promising tools to overcome such problems due to 3D
reconstruction from overlapping images without disturbing the surface.
This study presents the structure from motion (SfM) technique for
three-dimensional reconstruction using video and images of a large
landslide which occurred on 13 August 2017 at Kotropi, Himachal Pradesh,
India. In this study, we have used an Unmanned Aerial Vehicle (UAV) –
DJI Phantom 3 Advanced to collect high-resolution images and video of
landslide. A total of 98 images and 9 videos of 12:18 minutes duration
were captured during the drone flight on 23 March 2019 covering the
whole landslide and surrounding areas. The images were collected in
unorganized manner for covering the whole landslide in the limited
amount of time. We have used videos for coarse reconstruction and
high-resolution images for fine reconstruction of landslide. The whole
model was developed in two parts using MeshRoom and later merged using
co-registration in CloudCompare. Based on feature detection technique,
scale invariant feature transform (SIFT), image features were
automatically detected, described, and matched between photos. A bundle
block adjustment is performed on the matched features to identify the 3D
position and orientation of the cameras, and the XYZ location of each
feature in the photographs resulting in a sparse 3D point cloud.
Finally, meshing is carried out using 3D Delaunay tetrahedralization.
For visualization and analysis of final 3D model, open source software
CloudCompare/MeshLab was used. The morphological parameters such as
length, width, height, perimeter, area and volume were computed from the
3D model. From field observations and image analysis we will show that
UAV-based image in combination with 3D scene reconstruction algorithms
provide a flexible and effective tool to map and monitor large
landslides such as Kotropi landslide of Himachal Pradesh.