Intersection fields for interactive global illumination

Pacific Graphics 2005Pacific Graphics 2005

Zhong Ren Wei Hua Lu Chen Hujun BaoZhong Ren Wei Hua Lu Chen Hujun Bao

State Key Laboratory of CAD&CGZhejiang 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

(ai, bj)

(ck, dm)Slice(ai, bj)

l(i, j, k, m)

Generating IF

Rasterize

Object Space Screen 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)

IndexTable

Data compression

Local/Global IF

…

…

… …

…

…

Computation model

)(),()( pGSpFpEk

k

),(),(),(

),(

),(),(),(

SpVSpHdSA

qpvisdSSph

dSqpvisSphSpF

s ss

S

)(),()()()( 1,, puuGuVuHpE M

kSMSM kk

Local IrradianceMap

Visibility RatioMap

Indirect IrradianceMap

Computation model

Intersection fieldScene data

Photon TracerVisibility SolverLI Shader

IF Generator

Synthesizer

LIM VRM IIM

Local Irradiance Map

M

Sk

LIM – H(M,SLIM – H(M,Skk)) •Pixel Shader•Divide Sk into patches •Render-to-texture•Updating issue

Visibility Ratio Map

M

Sk

VRM – V(M,SVRM – V(M,Skk))

•Query IF for visibility sample•Reconstruction•Render-to-texture •Updating issue

Indirect Irradiance Map

M

IIM – G(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!