Improvement of the Edge-based Morphological (EM) method for lidar data filtering

Filtering is a crucial step in lidar data processing. The Edge-based Morphological (EM) filtering method proposed by Chen et al. (2007, Photogrammetric Engineering and Remote Sensing, 73, pp. 175-185) is fast and can be applied to different land use and land cover types. However, it requires a large number of parameters. It is challenging for average users to tune these parameters without a good understanding of the algorithm. This study introduces a new method to identify buildings so that the total number of parameters to be tuned is reduced from 7 to 2. Even with fewer parameters being tuned, it was found that the average filtering error slightly decreased compared to the original algorithm when tested with the benchmark dataset provided by the International Society for Photogrammetry and Remote Sensing (ISPRS) Commission III/WG3. This is a useful contribution to the original algorithm given that it can achieve increased accuracy in a simpler way for users.