Quirin Meyer 1, Christian Eisenacher 1, Marc Stamminger 1, Carsten Dachsbacher 2 1 Erlangen-Nuremberg University, Department Informatik, Computer Graphics 2 Stuttgart University, VIS/VISUS

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  oracle?

 Link & hierarchy creation ◦ Hierarchy of patches

 Link & hierarchy creation ◦ Hierarchy of patches ◦ Hierarchy of links

 Link & hierarchy creation ◦ Hierarchy of patches ◦ Hierarchy of links  Transport light over links ◦ Keep hierarchy consistent ◦ Convolute with BRDF Create Links and Patch Hierarchy Simulate Light Transport Display  Display

 Link & hierarchy creation ◦ Hierarchy of patches ◦ Hierarchy of links Create Links and Patch Hierarchy Simulate Light Transport Display Simulate Light Transport Display  Transport light over links ◦ Keep hierarchy consistent ◦ Convolute with BRDF  Display GPU APPROVED

 Link creation still not on the GPU!  Problem on the GPU: ray casts for explicit visibility computation  New radiosity-like methods: ◦ Implicit Visibility [Dong07] ◦ Antiradiance [Dachsbacher07] ◦ Directional discretization Create Links and Patch Hierarchy Simulate Light Transport Display

 Goal: interactive global illumination  Visibility without ray casts allows patch hierarchy & link creation on the GPU  How to parallelize? ◦ Parallelism over the links ◦ Parallel job queue of links ◦ Mark used patches on the way to create a compact hierarchy of patches

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... oracle scan refine Until all links are ready!

64 bins ≡ 1 KiB 128 bins ≡ 2 KiB 256 bins ≡ 4 KiB

4253 Nodes ~ 4 MB17745 Nodes ~ 17 MB

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 Bin search  Link recoding  Form Factors  Implicit Visibility: Only keep shortest link  Topology

Link Creation: 24.2 ms Links:1.1 M Patches:21 k Bins:256 3 Iter. AR:53.1 ms Total FPS:11 fps

Antiradiance Implicit Visibility bins

1 Iteration 2 Iteration 3 Iteration Link Creation bins 12 fps 25 fps 50 fps 81 fps

1 Iteration 2 Iteration 3 Iteration Link Creation bins fps

Oracle Scan Refine Mark Recode Topology Min. Link IV only 1.1 M Links and 21 k Patches 2.9 ms 8.0 ms 1.2 ms 5.5 ms 6.3 ms 5.6 ms 0.3 ms

 Link creation time ~ solution time  Surprisingly simple kernels  Performance ◦ Transferring 1 M links from CPU to GPU13.2 ms ◦ Creating 1 M links on the GPU24.2 ms  Global atomics not evil

 No clustering („surfel-hierarchy“ ) [Dong07]  Maximum depth of perfect patch tree  Memory consumption: 82.9 MB for 21 k patches

 Link creation for hierarchical radiosity on GPU ◦ Link hierarchy ◦ Compact patch hierarchy  Two methods ◦ Antiradiance: 50 M links / second ◦ Implicit Visibility: 15 M links / second ◦ Dynamic, interactive scenes

 Link Creation ◦ BF-refinement ◦ Clustering  Antiradiance/Implicit Visibility ◦ Reduce storage costs per node ◦ Light transport