HiT: hierarchical triangular model for variable representation of terrain

Representation of terrain at arbitrary level of accuracy is considered as a basic requirement for terrain rendering and ground analysis in a number of visual applications. In all of such applications, there exists compromise between the desire for accuracy and the amount of information to be needed. For visualization of terrain, an efficient way to achieve the compromise is to display an approximation at high accuracy in specific areas of interest, while a coarse approximation is used over the other areas. And, for analytical purpose, it is efficient to employ a proper approximation of terrain with maximum precision for given tasks. Multiresolution terrain models offer the possibility to visualize and analyze terrain in 3D at different levels of precision. In this paper, we focus on a multiresolution representation of triangulated terrain, called HiT model, which can efficiently support rendering operations at interactive rate as well as analytical operations. HiT model is a new type of unified model for multiresolution description of triangulated terrain. In this paper, we'll describe HiT model in a formally way. We also presents algorithms for extraction of constant approximation and view-dependent approximation.