Bulletin of the Geological Society of Malaysia, Volume 68, December 2019, pp. 151 – 158
Sharan Kumar Nagendran1,2, Mohd Ashraf Mohamad Ismail1,*, Wen Yan Tung1
1 School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, Penang, Malaysia
2 Centre of Excellence for Engineering & Technology (CREaTE),
Public Works Department (JKR), Alor Gajah, Melaka, Malaysia
* Corresponding author email address: ceashraf@usm.my
Abstract: Photogrammetry advancement in the field of geotechnics is able to provide useful preliminary data in a short time and with minimum resources. The data acquisition for photogrammetry processing was done utilizing the imagery from a low-cost unmanned aerial vehicle (UAV). Commercial drone by DJI, Phantom 4 Pro was used to take aerial and side images of the rock slope. Good overlapping of the images is very important to generate a very dense 3D model. Ground control point was established to georeferenced the output of photogrammetry, so that it represents the real site scale and coordinates. Photogrammetry using structure from motion technique (SfM) is able to generate three-dimensional model of the specified study area. 3-D model of the rock slope was analyzed to extract the geological planes using CloudCompare software with the aid of FACET plugin. 3-D dense cloud point generated from the photogrammetry process was the input file to the CloudCompare software. Traditional method of using scan line survey was carried out to check the adequacy of the geological plane extraction data from photogrammetry survey output. Extraction of geological planes through FACET plugin provides information on major discontinuity sets and the orientation of the planes. Then, the dip/dip direction obtained was compared with scanline survey. The discontinuity datasets obtained from the CloudCompare was compared with the scan line survey. Results showed the difference is not more than 20 %. Therefore, application of photogrammetry through CloudCompare software provides reliable and accurate measurement.
Keywords: Photogrammetry, rock slope, FACET, geological plane extraction, scanline survey
DOI : https://doi.org/10.7186/bgsm68201916
