Intersection fields for interactive global illumination Pacific Graphics 2005 Zhong Ren Wei Hua Lu Chen Hujun Bao State Key Laboratory of CAD&CG Zhejiang University, P.R. China

Overview Interactive global illumination Illumination engineering Animation preview Visibility bottleneck Intersections, intersections … Intersection(O(log(n))) to Query(O(1)) GPU?

Previous Work Radiosity Illumination network[Bucklew89] Monte Carlo Method Selective photon tracing GPU based photon mapping[Purcell2003] Global ray-bundle tracing[Kalos98, 99, 03]

Intersection field – the idea Ray-scene intersection points are places where light-object interactions take place.

Intersection field – the idea … …

Parameterization (a, b) (c, d) Base plane Slice(a, b) l (a, b, c, d)

Discretization (a i, b j ) (c k, d m ) Slice(a i, b j ) l (i, j, k, m)

Generating IF Rasterize Object SpaceScreen Space Line Space 2-step scan conversion

Scan conversion

Data organization (p, l, T) (x|y|z, T) Intersection Record … Line Record (i, j, k, m) … Page Record (i, j, k) Index Table

Data compression

Local/Global IF … … … … … …

Computation model Local Irradiance Map Visibility Ratio Map Indirect Irradiance Map

Computation model Intersection field Scene data Photon Tracer Visibility Solver LI Shader IF Generator Synthesizer LIM VRMIIM

Local Irradiance Map M SkSk LIM – H(M,S k ) Pixel Shader Divide S k into patches Render-to-texture Updating issue

Visibility Ratio Map M SkSk VRM – V(M,S k ) Query IF for visibility sample Reconstruction Render-to-texture Updating issue

Indirect Irradiance Map M IIM – G(M) Query IF for intersection points Accumulation Render-to-texture

Results 93M Lines (76x127x76x127) 72.6MB/113.0MB Intersection Field ~35,000 Photons

Contribution Visibility Representation Rendering Framework

Limitation Storage cost High frequency effect

Discussion

Thanks!