Representation techniques for real-time visualization of hybrid terrain models

Abstract

In this thesis several techniques to generate and visualize 3D hybrid terrain models are proposed which can integrate geographic data from heterogeneous sources, combining the benefts of coarsegrained grid-data and fne-grained irregular data without requiring a remeshing process that would modify the original datasets. Multiresolution rendering of the obtained representations are supported in the large regular areas, and in some cases in the whole hybrid model. All these methods are based in a local tessellation approach which can selectively rebuild the adaptive tessellation between the regular and irregular meshes of the models during the interactive visualization process. This approach was originally developed in the Hybrid Meshing algorithm developed by some members of the research group. An exhaustive analysis of this algorithm is presented and different extensions and improvements are proposed to avoid the preprocessing phase and to leverage the parallelism of modern GPUs. Two new methods are also proposed: the EHM and the EDP proposals. The EHM algorithm supports multiresolution rendering of the whole hybrid model, both in the base regular grid as well as in the high resolution irregular meshes. The EDP algorithm proposes the use of the external edges of the irregular meshes as the fundamental primitive to tessellate the boundaries of both types of meshes, simplifying the preprocessing phase and minimizing the insertion of vertices in the irregular mesh.