DIGITAL TERRAIN MODELS FROM AIRBORNE LASER SCANNER DATA - A GRID BASED APPROACH

Since Airborne laser scanning sensors are operational and the data capture, including the calculation of the exterior orientation by using GPS and INS, has reached a high level of automation, the focus has turned on the development of algorithms to extract information from the 3D point cloud. The main tasks are the derivation of terrain information, forest parameters or the extraction of buildings. Since terrain information also affects the calculation of forest parameters and gives an input to building extraction, many different approaches were developed in the past years to derive highly accurate digital terrain models. Most of these approaches, like mathematical morphology, weight iteration or triangulation, work with the 3D data points itself. This paper presents an approach that is based on the rasterization of data points which allows the usage of fast digital image processing methods for the calculation of DTM’s. The algorithm consists of a hierarchical approach in combination with a weighing function for the detection of raster elements that contain no ground data. The weighing function considers the terrain shape as well as the distribution of the data points within a raster element.