A Study Of Terrain Surface Reconstruction Algorithms

Surface reconstruction has broad application prospects in geography information system CAD and converse project. There are two methods in terrain surface reconstruction, which are indirect and direct reconstruction. Direct reconstruction is that using some data structure and surface reconstruction method to express the whole terrain surface by terrain data. Indirect reconstruction is that consummate terrain surface, construct the topology relationship of TIN (Irregular Triangular Network) .This paper discusses two basic problems. There are triangulation rule and topology reconstructruction. In the TIN triangulation rule, we analysis the existing triangulation rule and then give a new triangulation algorithm which considering the elevation information. The algorithm is called standard deviation rule.This paper describes standard deviation rule which uses x, y and z coordinate in triangulation. So it chooses the good shape triangles in space after computing. The result of triangulation is triangles which having good shapes in space. The TIN terrain surface is more near to real terrain surface and thinking logic. We explain the standard deviation, how to compute and why use it. Then provide the algorithm steps based on it. Finally, through an example and comparison analyse of algorithms we show the advantages of standard deviation rule.In the topology reconstructruction, it takes the idea of hash function into topology relationship to reconstruct the point topology and surface topology. Then through an experiement, we validate the algorithm. First, use hash function to express the obvious topology relationship of TIN fastly from point coordinate file and triangle file. That is, create the exclusive point coordinate file and triangle file which showed by point number, and find out adjacent triangles which having same side, so we build the topology relationship of triangles.The paper designs programme of the algorithms, it has some theory value and application value to 3DGIS, computer graphics and converse project. We will have some research on the exclusion of standard deviation rule and the application of hash function in GIS vector topology structure.