Based on a rasterization of the data, which allows the usage of fast digital image processing methods, the algorithm combines a hierarchical approach and a weighing function for the detection of non terrain raster elements. The weighing function considers the terrain shape as well as the distribution of the data points within a raster element. The hierarchical approach generates DTMs with 9, 3 and finally 1 meter resolution. This technique helps to remove large buildings or areas with dense vegetation.
The 60 km² DTM with 1 meter resolution (figure 2) was generated without tiling and the verification of the results are presented in table 1.