(A) continuous level-of-detail parametrization of polygonal meshes

Abstract

The level-of-detail(LOD) representation is a powerful scheme to increase the rate of frame update by software technique. The early approach is static simplification which considers constant LOD over all regions of mesh. On the other hand the view-dependent simplification(VDS) is more powerful than static simplification since it can simplify substantially the clipped out or backface culled regions which are not visually important. General VDS algorithm consists of two stages; presimplification and interactive visualization. The main problem of VDS algorithm is that the overhead of the interactive visualization is large. Therefore in this thesis a new VDS algorithm, called Level-of-detail parametrization(LP), is proposed to reduce the overhead of the interactive visualization. At the presimplification stage, a new hierarchy of mesh, region tree, is introduced. First a mesh is partitioned into a set of leaf regions and the higher level regions are created by merging lower level regions. Then multiple LOD versions are created for all regions. At the interactive visualization stage, active regions which should be rendered are determined, each of them is assigned a LOD determined by considering the relation between the view-point of observer and the region, and then the LOD version corresponding to the assigned LOD is rendered. Results show that the overhead of the interactive visualization takes only 1.5% of total frame time, which is quite smaller than 15% of [1]. Moreover smooth LOD transitions(geomorphs) can be constructed on the fly for continuous motions of observer.