Research Of Terrain Simplification Technology Based On Digital Elevation Model

Terrain simplification is an effective means to alleviate contradiction between immensity of data and limited storage of computer. It means preserve the whole terrain characteristic accord with a necessary precision, and then reduce the amount of terrain data to the full.There are many algorithms of terrain simplification. An algorithm has its own terrain simplification index. Variance of result of terrain simplification always exists among different indices. This paper creates a new concept, which is named reliability of preserve terrain characteristic, in order to estimate them quantificationally. At first, we construct a stimulant digital elevation model by a certain resolution in gauss surface and calculate gauss curvature of each grid point, which is regarded as true value to terrain simplification index. Then, Five terrain simplification, which are local elevation error, surface-simulated, plan curvature, profile curvature and max-angle-between-vector, can be calculated based on the stimulant DEM and we can obtain their reliabilities of preserve terrain characteristic compare them with real value-gauss curvature. Finally, we analyze them and find out their advantages and disadvantages. Furthermore, macro-estimation of the five terrain simplification indices is obtained, which is as follows: â‘  to the potential of reflecting terrain characteristic, the index based on normal vector is better than the others; â‘¡their reliabilities linearly ascend as terrain simplification ratio reduce; â‘¢their sorts are liable to terrain and resolution; â‘£their reliabilities are steady in the same resolution. Finally, we test research result on a lot of real terrain and find that it is all right.This paper also creates another terrain simplification index based on principle of spatial vector, which is named orthodox-vector-projection. It reflects the whole characteristic of local terrain cell effectively. In order to testify the issue that terrain simplification index of orthodox-vector-projection is better than others in the way of reflecting the whole characteristic of local terrain cell. Firstly, the issue is demonstrated from the point of theory. Secondly, some research fruits ofcomparison analysis between orthodox-vector-projection and above five terrain simplification indices are achieved, research show that reliabilities of preserve terrain characteristic of orthodox-vector-projection is the best among them and its level is quite high. At last, research result is testified based on a lot of real DEM.