3D GIS generally have very complex data models. In adapting these systems to the Internet, one has to take into account tire limited computational power of the typical personal computer and the limited network bandwidth available to casual Internet users. For quality of service management of interactive 3D GIS presentations, feature preserving data reduction techniques are of critical importance. The technique discussed in this paper deals with terrain modeling. The terrain surface usually exhibits significant spatial coherence. Such data coherence can be found in grid meshes regardless of their resolutions. The mesh simplification algorithm proposed here reduces the geometric complexity in grid meshes by taking advantage of this coherence.
