3D Digital Outcrop Model for Geological Structure Analysis in Mae Moh Coal Mine, Lampang Province, Thailand

The advancement of unmanned aerial vehicles (UAVs) replaces traditional survey methods and provides more accurate, complete, and higher-resolution photographs than traditional aerial images. Due to the development of new surveying methods, UAVs were taken to survey the eastern Mae Moh coal mine, Mae Moh district, Lampang province, Thailand, to create a 3D digital outcrop model. Geologically, the Mae Moh coal mine forms a graben structure in which the basin's center moves downward relative to the east and west high mountains. To create the 3D model, the UAV or drone was flown over three outcrop stations to capture details of outcrops in the top and 3D views. Computer vision processing complies with aerial images from UAVs to represent bedding planes of coal seams and exposed fault characteristics. The efficiency of measuring orientations of geological structures derived from the 3D model and actual field data reveals that bedding planes and fault planes orient in a similar direction. Regarding the fault planes, the percentage error of strike ranges from 1.5% to 8.0%, whereas the percentage error of dip angle ranges between 2.4% and 2.7%. For the bedding planes, the percentage error of strike ranges from 0.5% to 10.5%, while the percentage error of dip angle ranges between 9 % and 27 %. Although the efficiency of measurements on geological structures from the 3D digital outcrop model needs to be improved, using UAVs will help develop the quality of topographic and geological surveys in the future.