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Order-Independent Texture Synthesis

Order-Independent Texture Synthesis. Li-Yi Wei Marc Levoy. Gcafe 1/30/2003. Previous Work. Statistical Synthesis general, requires only a sample cannot be evaluated randomly on the fly Procedural Synthesis evaluation on the fly (e.g. Perlin noise) efficient

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Order-Independent Texture Synthesis

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  1. Order-Independent Texture Synthesis Li-Yi Wei Marc Levoy Gcafe 1/30/2003

  2. Previous Work • Statistical Synthesis general, requires only a sample cannot be evaluated randomly on the fly • Procedural Synthesis evaluation on the fly (e.g. Perlin noise) efficient less general, hard to set parameters

  3. Goal Combine Advantages from both Camps: • general as statistical methods • generate new textures from a given example • flexible as procedural methods • evaluate texels on demand • result always identical regardless of evaluation order

  4. New Algorithm Key Ideas: • multiple generations • neighborhood contains only old values • lower generations, lower resolutions • pyramidal cache • Details: • see the paper (4 pages only)☺

  5. Example Generation 2 Generation 1 Generation 0

  6. Level 3 Level 2 Level 1 Level 0 Generation 2 Generation 1 Generation 0 Example

  7. Single Polygon 19% requested 23% computed Rendering Mipmap Texture

  8. Quake Texture 64  64 Unnatural repetition Texture 512  512 Less repetition

  9. Ray Casting Scene Texture

  10. Simulation Result

  11. Future Work Implementation as fragment shader☻

  12. End

  13. Overview Procedurally Statistical Texture Synthesis • algorithm • architecture Applications • procedural shader • interactive tools • texture mapping hardware

  14. Texture Mapping • Bottleneck in graphics pipeline • computation • texture memory access • Solutions • caching • pre-fetching • compression [VQ] texture image

  15. Copy Search noise Input pyramid Output pyramid How It Works noise

  16. Goal • Combine advantages from both camps • general • independent texel evaluation

  17. Order-Independent Texture Synthesis • Simple modifications of our old algorithm • evaluate pixel in any order • consistent result (given the same initial value) • time complexity depends only on neighborhood size (not on output texture size) • interface much like procedural synthesis • greater flexibility • more computation

  18. Problem with Old Algorithm dependency graph level row col 0 -1 0 0 +1 0 0 0 -1 0 0 +1 -1 0 0 cycles in the dependency graph!

  19. Order-independent evaluation New Algorithm dependency graph Keep multiple generations Acyclic dependency graph level row col generation 0 -1 0 -1 0 +1 0 -1 0 0 -1 -1 0 0 +1 -1 -1 0 0 newest

  20. Implementation : Cache • no full pyramid required, use cache instead • output determined solely by lowest resolution

  21. Algorithm evaluate (level=L, row = x, col = y, generation = g) 1. If in cache, return it 2. Collect neighborhood level row col generation L x-1 y g-1 L x+1 y g-1 L x y-1 g-1 L x y+1 g-1 L-1 x y g Cached? evaluate (L, x-1, y, g-1) 3. Find best match

  22. Generation 2 Generation 1 Generation 0 Level 3 Level 2 Level 1 Level 0 Cache Footprint : Single Pixel

  23. Generation 2 Generation 1 Generation 0 Level 3 Level 2 Level 1 Level 0 Cache Footprint : S

  24. Generation 2 Generation 1 Generation 0 Level 3 Level 2 Level 1 Level 0 Cache Footprint : Sphere

  25. Generation 2 Generation 1 Generation 0 Level 3 Level 2 Level 1 Level 0 Cache Footprint : Random

  26. Level 3 Level 2 Level 1 Level 0 Generation 2 Generation 1 Generation 0 Cache Footprint: Single Pixel 1148 pixels!

  27. Level 3 Level 2 Level 1 Level 0 Generation 2 Generation 1 Generation 0 Cache Footprint:Poisson Points

  28. Level 3 Level 2 Level 1 Level 0 Generation 2 Generation 1 Generation 0 Cache Footprint:Circular Pattern

  29. Cache Usage Statistics random sphere Percentage of cache used ideal (linear) Percentage of input requested

  30. Cache Coherence

  31. Quality Comparison old new

  32. Quake 44% requested 48% computed Input Texture 64  64 Texture 512  512

  33. QuickTime VR invisible Input Original Result

  34. Simulation Result

  35. Architecture Design

  36. Pitfalls • not feasible for current hardware • can only be applied to repeating patterns

  37. Finished Work • Verification using an infinite cache

  38. Ongoing Work • Measuring and understanding various parameters • cache size, associativity, replacement policy • evaluation order for missing pixels (register allocation) • benchmarking • Combination with patch-based texture synthesis • patch boundaries? • complicate caching behavior

  39. Motivation Texture mapping is important Texture mapping can be a bottleneck Solution: Texture Mapping by Synthesis

  40. Hardware Trend •  Computation >>  Memory Speed • Transform memory access into computation

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