Generalization Of Dense Digital Terrain Models While Enhancing Important Objects

Laser altimetry is a leading technology for the extraction of information of physical surfaces, and hence it is the main source for generating a dense digital surface of the terrain. This results in data sets with a very high density and accuracy. This high quality data sets bring about a massive amount of data, which is hardly manageable or accessible. Particularly the efficient graphic representation of this data in real time appears to be difficult. To reduce the three dimensional information and make it manageable, methods of generalization and simplification are needed. During the process of generalization, important objects within the DTM have to be emphasized, to guarantee their perceptibility. The objects to be emphasized differ according to the intention of the generalization. In the context of a 3D-city modelling, especially buildings and their structures have to be generalized. Whereas for the purpose of terrain surface visualization, special attention has to be given to the enhancement and generalization of topographic objects like dams or streets. For the time being, the main focus of this work is laid on the enhancement and generalization of street objects. The streets in the DTM are enhanced by widening them to either side of the middle axis. Changing the height values within the broadened street brings about discontinuities in the adjacent regions. For this reason, also the height values in this regions have to be adapted, however the extent of the area to be modified has to be defined. In addition, a weighting function for the adaptation has to be chosen. Another option is the displacement and thus a compression of that parts of the surface, which lie between the broadened streets. The different options for the adjustment of the terrain model after t..