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Modeling the topography of fault zone based on structure from motion photogrammetry

The quantitative study of active faults is highly dependent on high-precision and high-resolution topographic data. Though Light Detection and Ranging (LiDAR) technology can provide such data, its high cost greatly limits its use in many geoscience applications. Recently, the Structure from Motion (SfM) photogrammetry shows a great potential to provide topographic information with high precision, but at significantly lower costs than the laser scanning survey. In this study, the applicability of SfM photogrammetry method in modeling the topography of fault zone was investigated by using images acquired with a low-cost digital camera mounted on an UAV. The resolution and accuracy of the SfM-derived topographic data was evaluated in detail using existing airborne LiDAR data as a benchmark. The results show that the SfM photogrammetry method can produce a point cloud with the density seventy times higher than the airborne LiDAR. Furthermore, considering the errors in LiDAR data itself, and the precision of the SfM-derived point cloud is comparable to that of the LiDAR point cloud, demonstrating that the SfM photogrammetry method is an inexpensive and effective alternative to airborne LiDAR for the topography modeling of fault zone.