Interactive Rendering of Meso-structure Surface Details using Semi-transparent 3D Textures

Several techniques have been introduced to display meso-structure surface details to enhance the appearance of complex surfaces. One strategy is to avoid altogether costly semi-transparency in interactive contexts. However when dealing with hierarchical surface representations (important to filtering) and complex light transfers, semi-transparency must be treated. We propose a method that combines in a novel way multiple techniques from hardware rendering and volume visualization in order to render on current graphics hardware semitransparent meso-structure surface details stored in a 3D texture. The texture is mapped to an outer shell defined by tetrahedra extruded from the surface triangular mesh. The tetrahedra are first sorted on the CPU to be rendered in correct order. The attenuated color for each ray traversing each tetrahedron is efficiently computed with a hardware voxel traversal algorithm. The resulting structure is general enough to simulate at interactive rates from semitransparent surface details to opaque displacement maps, including several surface shading effects (visual masking, self-shadowing, absorption of light).