docRendering a complex world - Cornell University Program of
download 
Plainte Transcription
Rendering a complex world - Cornell University Program of
Rendering a complex world François X. Sillion i MAGIS* Grenoble, France *A joint research project of CNRS, INRIA, INPG and UJF How complex can it be? Probably no need to render this! iMAGIS Real-world complexity? ü The world is not geometric! – Geometry = abstraction ü Illumination effects – Extended, multiple, spectral sources ü Evolution over time – Life, aging, movement, etc. iMAGIS Complex geometry ü Rendering – Cull / select relevant scene elements – Simplify geometric model – Use image-based model ü Illuminating complex geometry – Cull? Not so easy… – Simplify? Need to relate computed illumination to displayed model. iMAGIS Impostors for accelerated rendering ü Use image to extract visible geometry ü Simplify image information iMAGIS Creating impostors Choose layers of geometry according to relative visibility and masking criteria iMAGIS Multi-mesh impostors [Animation fxsSMI.mov] QuickTime™ et un décompresseur Animation sont requis pour visualiser cette image. Single mesh impostors [Animation fxsMMI.mov] QuickTime™ et un décompresseur Animation sont requis pour visualiser cette image. Multi-mesh impostors Decoret, Schaufler, Sillion, Dorsey, EUROGRAPHICS ’99 iMAGIS Dealing with complex illumination ü Reflectance models – Anisotropic, spectral, limiting cases, polarization… ü Spectral calculations ü Light sources and daylight Standard representations and Hierarchical algorithms are needed iMAGIS Global Illumination effects ü When do we need them? ü Hierarchical techniques ü Partitioning and parallel calculations ü Deterministic methods cannot be applied to full models iMAGIS Can radiosity be useful? ü Pre-computed illumination for interactive visualization ü Reservoir of illumination information for local shading ü Approximate or partial results iMAGIS Computing less acurate images ü Application-dependent accuracy ü Perceptual assessment of result quality ü Difficulty of hierarchical radiosity refinement iMAGIS Shadow computation using convolution Source image Blocker image Shadow mask iMAGIS Soler, Sillion SIGGRAPH ’98 iMAGIS Radiosity applications Model courtesy of BMW iMAGIS Rendering local complexity ü Hierarchical modeling ü Generalized textures – View-dependent, volumetric, 3D, 4D… ü Abstraction of reflectance/scattering behavior iMAGIS Neyret Neyret Graphics Graphics Interface Interface 96 96 iMAGIS A world in motion ü Complex time-dependence of rendering parameters Example of lava flow ©Fabrice Neyret [Animation fxsLAVA.mpg] QuickTime™ et un décompresseur sont requis pour visualiser cette image. iMAGIS Lava flow example ©Fabrice Neyret iMAGIS Questions ü Hierarchy of representations and algorithms – Energy exchange, local detail ü Adapt to application – Acceptable approximations (shadows) – Interactive rendering ü Make better use of real images... ü Complexity of… rendering! iMAGIS
