Micro-Rendering for Scalable,Parallel Final Gathering

Tobias Ritschel1 Thomas Engelhardt2 Thorsten Grosch1

Hans-Peter Seidel1 Jan Kautz3 Carsten Dachsbacher2

1Max-Planck-Institut Informatik 2VISUS / University Stuttgart 3University College London

SIGGRAPH Asia 2009Friday, 18 December, 2009, Yokohama, Japan

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

MOTIVATION

Without global illumination With global illumination

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

PREVIOUS WORK

Finite Element: AntiradianceDachsbacher et al. 2007

Finite Element: Implicit VisibilityDong et al. 2007

(Parallel) ray-tracingWang et al. 2009

PRT: Spherical HarmonicsSloan et al. 2004

PRT: WaveletsNg et al. 2004

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

PREVIOUS WORK

Instant radiosityKeller 1997

Many-lights approachWalter et al. 2005Hasan et al. 2007Chevlak-Postavak et al. 2008

VPL visibilityLaine et al. 2007Ritschel et al. 2008

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

PREVIOUS WORK

Ambient OcclusionZhukov 1998Landis 2002Shanmugam and Orikan 2005Ritschel et al. 2008

Disk-based Color BleedingBunell 2005Christensen 2008

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

IDEA

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

A TRANSPOSED PIPELINE

Global Illumination =

Several ten-thousand, tiny scene renderings for each frame

for each pixel...

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

Q-SPLAT

Szymon Rusinkiewicz and Marc Levoy:QSplat: A Multiresolution Point Rendering System for Large MeshesSIGGRAPH 2001

Michelangelo:St. Mathew (unfinished) Before 1501

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

1-pixelsizednodes

Q-SPLAT

Biggerthan pixel

Biggerthan pixel

Pixel-sized

Biggerthan pixel

Pixel-sized Pixel-sized

Pixel-sized

Biggerthan pixel

Biggerthan pixel

Pixel-sized Pixel-sized

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

TREE REPRESENTATION

Position, radius

Normal cones

Average intensity

... millions of ...

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

Mic

ro-fr

ameb

uffer

Q-SPLAT GATHERING

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

Q-SPLAT GATHERING

Mic

ro-fr

ameb

uffer

Mic

ro-d

epth

buffe

r

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

PREVENTING HOLES

Mic

ro-fr

ameb

uffer

Mic

ro-d

epth

buffe

r

Leaf

Leaf

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

PREVENTING HOLES

Without ray-casting With ray-casting

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

DIFFUSE BRDF

Light Diffuse BRDF

Regular z-buffer

ʃ • =

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

SPECULAR BRDF

Light Specular BRDF

Regular z-buffer

ʃ • =

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

BRDF WARPING

Light

Warped z-buffer

ʃ =

BRDF

•

Area

•

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

BRDF WARPING

Light

Warped z-buffer

ʃ =

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

BRDF WARPING

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

SCALABILITY: OCCLUSION

24x240.7 frames / second

16x161.5 frames / second

8x83.2 frames / second

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

VS. IMPERFECT SHADOW MAPS

Ritschel et al.: Imperfect Shadow Maps (Previous)SIGGRAPH Asia 2008

5 frames / second

Ritschel et al.: Micro-Rendering (Ours)SIGGRAPH Asia 2009

5 frames / second

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

SCALABILITY: MATERIALS

1x12x2

4x4

Kd = 1Kd = 0.5, N = 5Kd = 0, N = 20

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

MULTIPLE BOUNCESNo Bounce 1 Bounce

10 frames / second2 Bounces

5 frames / second

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

MULTIPLE BOUNCES

TreeDirectlLight

TreeIndirect light

Image2-bounce indirect light

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

GATHERING PHOTON MAPSSurfels lit by photon mapping density estimate Final gathering from lit surfels, 2 frames / second

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

CONCLUSIONMicrorendering computes final gathering for large and dynamic scenes with

glossy materials in parallel

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

FUTURE WORK

1. Complex deformations result in an in efficient tree... a body of work existst for ray-tracing

2. Adaptivity in screen space... also a body of work for radiance and irradiance caching

3. Reduce local memory footprint... we think we will get it down by an order of magnitude

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

THANK YOU!

We acknowledgemens

Michael WandElmar EisemannRobrt StrzodkaRober HerzogZhao DongRobert W. SumnerJovan PopovicStanford 3D Scanning Repository

Internal ReviewInternal ReviewDiscussionDiscussionDiscussionAnimal animationAnimal animation3D models

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

AO Bounces Specular Parallel Visibility

Disk-based AOBunnell 200) Yes Yes No Yes None

Hemispherical RasterizationKautz et al. 2005

Yes Maybe No Yes Rasterize / Forward

Pixar Color BleedingChristensen 2008 Yes Yes Maybe Maybe Rasterize /

Forward

Micro-rendering Ritschel et al., 2009 Yes Yes Yes Yes Rasterize /

Forward

LightcutsWalter et al., 2005 Yes Yes Yes Maybe Raytracing /

Backwards

HIDDEN SLIDE 1

Micro-Rendering for Scalable, Parallel Final Gathering (Ritschel et al.)

HIDDEN SLIDE 2

Probability density

Cummulative density