Volumetric Surface Sculpting Volumetric Surface Sculpting

In computer graphics, two types of geometric representations are widely used: surfaces and volumes. Surfaces are in nitely thin skins de ning the boundary of an object, and have been successful in modeling realistic appearances. However, their lack of information about the solid nature of objects make them inadequate for many applications. Volumes represent the entire solid geometry of an object in a three-dimensional grid. Volumes, however, are ine cient and cannot achieve high resolutions since they must maintain information about internal geometry that is not pertinent to rendering realistic appearances. We have created a new, hybrid data structure, the volumetric surface, which combines the bene ts of surfaces and volumes. A volumetric surface represents solid materials in a thin region near the surface of an object in an e cient, multi-resolution data structure. Volumetric surfaces are thus designed to exploit the coherency of roughly surface aligned-layers of materials which are ubiquitous in real-world materials. Examples of such materials include wood, stone, and building facades. To demonstrate the utility of volumetric surfaces, we present a system for the interactive sculpting of weathering and erosion e ects on building facades. High-resolution sculpting of layers of solid brick, plaster, and mortar are not possible with surfaces or volumes alone. Volumetric surfaces are well suited to the representation and intuitive editing of such complex appearances. This thesis presents detailed algorithms for the sculpting system with a focus on e cient rendering and manipulation of volumetric surfaces. Thesis Supervisor: Julie Dorsey Title: Associate Professor