combining global and local virtual lights for detailed glossy illumination
DESCRIPTION
Combining Global and Local Virtual Lights for Detailed Glossy Illumination. Jaroslav Křivánek. Milo š Hašan. Philipp Slusallek. Kavita Bala. Tomáš Davidovič. Saarland University / DFKI. Cornell University. Charles University , Prague. Goal: Glossy inter-reflections. - PowerPoint PPT PresentationTRANSCRIPT
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Miloš Hašan
Jaroslav Křivánek
Philipp Slusallek
Kavita Bala
Combining Global and Local Virtual Lights for
Detailed Glossy Illumination
Tomáš Davidovi
čSaarland
University / DFKI
Cornell University
Charles University,
Prague
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Goal: Glossy inter-reflections
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• Indirect glossy highlights from complex geometry
Our new approach
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our approach: 6 minutes reference: 244 minutes
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• Unbiased methods– (Bidirectional) path tracing [Kajiya 86,
Lafortune el al. 93]– Metropolis light transport [Veach and Guibas
97]• Biased methods
– (Progressive) photon mapping[Jensen 2001, Hachisuka et al. 08/09]
– Radiance caching [Křivánek 05]• Scalable virtual light methods
– Lightcuts [Walter et al. 05/06]– Matrix row-column sampling [Hašan et al.
07/09]
Previous work
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• Instant radiosity [Keller 1997]• Approximate indirect illumination by
Virtual Point Lights (VPLs)1. Generate
VPLs
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Previous work – VPL rendering
2. Render with VPLs
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Previous work – VPL energy loss
energy loss
material change
[Křivánek et al. 10]
VPLs w/ clamping
GI reference
artifacts
VPL
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• Replace point lights by spheres [Hašan et al. 2009]
• Alleviates the energy loss but blurs illumination
Previous work – VSLs
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virtual spherical lights (VSLs) reference
blur
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• Compute the missing energy by path tracing[Kollig and Keller 2004]
• As slow as path-tracing everything (for glossy)
Previous work – Compensation
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indirect illumination
Compensation
ClampingInstantradiosity (VPLs)
Path tracing
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• Specific fast solution for each component
Our approach
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indirect illumination
Compensation
Clamping Global componentVisibility clust.
Local componentLocal VPLs
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• Solution of the global component
• Solution of the local component
• Results
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Outline
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Solving the global component
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• Light transport over long distances
• Handled by classic “global” VPLs
• Scalable solution: visibility clustering
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Global (clamped) component
local
global
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Review of MRCSPixels
Lights• Matrix interpretation
indirect illumination
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• Problem statement
= Σ (
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Review of MRCSPixels
Lights
)indirect illumination
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• Solution
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Review of MRCSPixels
Lights
)≈ Σ (
shadow maps for visibility
indirect illumination
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• Many VPLs neededfor shading– Shading is cheap
shade from all VPLs
• Cannot afford visibility for every VPL
• Key idea:Separate shading from visibility
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Visibility Clustering – MotivationLights
shading (all VPLs)visibility (representatives)
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Global solution overviewRow
sampling
Global solution (clamped)
Global VPL tracing
shading
Reduced matrix
visibility
Visibility clustering
Render lights withreps’ visibility
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• Clustering algorithm– Hierarchical splitting– Minimize the clustering cost
• L2 error of reduced matrix due to visibility approximation
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Visibility clusteringclusters
representatives
shading
visibility
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Visibility clustering resultMatrix row-
column sampling
Our visibility clustering
10k shadow maps 10k shading lights
5k shadow maps 200k shading lights
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Solving the local component
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• Localized light transport
• Less energy
• Solution: Local VPLs
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Local (compensating) component
local
global
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• Kollig & Keller compensation
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Review of compensation
3) Contribute
Clamped
energy
2) Connect
1) Shoot path
global
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• Our approach
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Local lights – idea
Create local light
Contribute to a tile
global
local
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• Our approach
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Local lights – technical solution
local
from tile pixels
Probability density
Jittertiles
global
local
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• Our approach
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Local lights – technical solution
One-samplevisibility
global
Clampedenergy = 0
Rejectlocal
50-75%2-4x speedup
• Key idea: Tile visibility approximation
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The complete local solution
Local solution(compensation)
Generate local lights
Reject zero contrib
Connect to global lights
Contributeto a tile
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The complete local solution
Local solution(compensation)
Global solution (clamped)
Indirect illuminationsolution
• Localized transport• Less energy• Reuse on tiles
• Long distance transport
• Most of the energy• Visibility clustering
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CPU/GPU cooperation
CPU
GPU
Generate & cluster globalVPL
Generate local VPLs
Render global VPLs
Render local VPLs
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Results
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Tableau
• shadow maps:
• global lights:
• local lights:
5,000
200,000
55,600,000
VSL: 6 min 16 sec
Our: 5 min 43 sec
reference: 244 min
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TableauVSL: 6 min 16 sec
Our: 5 min 43 sec
reference: 244 min
• shadow maps:
• global lights:
• local lights:
5,000
200,000
55,600,000
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Disney Concert Hall
• shadow maps:
• global lights:
• local lights:
15,000
200,000
13,500,000
Our: 2 min 44 sec
reference: 127 min
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Disney Concert HallVSL: 1 min 47 sec
Our: 2 min 44 sec
reference: 127 min
• shadow maps:
• global lights:
• local lights:
15,000
200,000
13,500,000
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Kitchen #1
Our: 4 min 16 sec
reference: 3343 min
• shadow maps:
• global lights:
• local lights:
10,000
200,000
25,100,000
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Kitchen #1
• shadow maps:
• global lights:
• local lights:
10,000
200,000
25,100,000
Our: 4 min 16 sec
reference: 3343 min
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Kitchen #1
• shadow maps:
• global lights:
• local lights:
10,000
200,000
25,100,000
VSL: 4 min 24 sec
reference: 3343 min
Our: 4 min 16 sec
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Kitchen #2VSL: 6 min 25 sec
Our: 5 min 28 sec
reference: 6360 min
• shadow maps:
• global lights:
• local lights:
10,000
300,000
17,100,000
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Kitchen #2
• shadow maps:
• global lights:
• local lights:
10,000
300,000
17,100,000
VSL: 6 min 25 sec
Our: 5 min 28 sec
reference: 6360 min
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Kitchen #2 – limitations
• Loss of shadow definition• Small loss of energy
Our: 5 min 28 sec reference: 6360 min
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• Highly glossy materials with GI• Split light transport
– Global component– Local component– Specialized methods for each
• Future work– Explore other solutions for global
component– Revisit split criteria (MIS instead of
clamping?) 40
Conclusions & Future Work
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Acknowledgements
• Marie Curie Fellowship PIOF-GA-2008-221716
• NSF CAREER 0644175, NSF CPA 0811680
• Intel and Intel VCI• Microsoft• Autodesk• German Research Foundation
(Excellence Cluster 'Multimodal Computing and Interaction‘)
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Thank you
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Kitchen #2 – PPM and SPPM• (Stochastic)
Progressive Photon Mapping
PPM: 26 min 40 sec
Our: 5 min 28 sec
SPPM: 27 min 49 sec