THE UNCERTAINTIES OF DOD UNDER FOREST COVER WITH MULTI-TEMPORAL AIRBORNE LIDAR DEMS

摘要

Methods of geomorphic change detection (GCD) may be applied to a wide range of time periods to measure erosion, deposition, and volumetric change. It is straight-forward to construct a DEM of difference (DoD) by subtracting one elevation model from another. The challenge is to recognize and minimize uncertainties in multi-temporal DEMs which are subjecting to uncertainties such as flight plan parameters, landscape conditions, land surface conditions and the overall environment during data acquisition. This paper reviews potential sources of error in DoD for sedimentation assessment of a water reservoir. A comparison is made to find the difference of volumes between simple DoD and masked DoD over which only landslide areas are used as stencil and forested area are masked. The result shows that 55% of the total volume is due to the uncertainties of forest cover. To minimize the effect of uncertainties under forest cover when applying simple DoD, a data-set aggregation method is proposed for further experiment in addition to the masked DoD method. It is concluded that though airborne LiDAR DEM is claimed to be accurate cares must be taken to treat the uncertainties when it is applied to measure erosion, deposition, and volumetric change.