Group 8 (2o3) Lin Yuan Xun Wu Yi Fan Dong Jiaxi Moo Jun Wei.
Order-Independent Texture Synthesis Li-Yi Wei Marc Levoy Gcafe 1/30/2003.
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Order-Independent Order-Independent Texture Synthesis Texture Synthesis Li-Yi Wei Marc Levoy Gcafe 1/30/2003
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Transcript of Order-Independent Texture Synthesis Li-Yi Wei Marc Levoy Gcafe 1/30/2003.
Order-Independent Order-Independent Texture SynthesisTexture Synthesis
Li-Yi Wei Marc Levoy
Gcafe 1/30/2003
Previous WorkPrevious Work
• Statistical Synthesisgeneral, requires only a sample
cannot be evaluated randomly on the fly
• Procedural Synthesisevaluation on the fly (e.g. Perlin noise)
efficient
less general, hard to set parameters
GoalGoal
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
New AlgorithmNew Algorithm
Key Ideas:– multiple generations– neighborhood contains only old values
• lower generations, lower resolutions
– pyramidal cache
• Details:– see the paper (4 pages only)☺
ExampleExample
Generation 2 Generation 1 Generation 0
ExampleExample
Level 3
Level 2
Level 1
Level 0
Generation 2 Generation 1 Generation 0
Single PolygonSingle Polygon
Rendering Mipmap Texture
19% requested23% computed
QuakeQuake
Texture 64 64Unnatural repetition
Texture 512 512Less repetition
Ray CastingRay Casting
Scene Texture
Simulation ResultSimulation Result
Future WorkFuture Work
Implementation as fragment shader☻
EndEnd
OverviewOverview
Procedurally Statistical Texture Synthesis– algorithm– architecture
Applications– procedural shader– interactive tools– texture mapping hardware
Texture MappingTexture Mapping
• Bottleneck in graphics pipeline– computation– texture memory access
• Solutions– caching– pre-fetching– compression [VQ]
texture
image
How It WorksHow It Works
noise
Input pyramid
noise
Output pyramid
Search
Copy
GoalGoal
• Combine advantages from both camps– general– independent texel evaluation
Order-Independent Order-Independent Texture SynthesisTexture 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
Problem with Old AlgorithmProblem with Old Algorithm
dependency graph
cycles in the dependency graph!
level row col
0 -1 0
0 +1 0
0 0 -1
0 0 +1
-1 0 0
New AlgorithmNew Algorithm
level row col generation
0 -1 0 -1
0 +1 0 -1
0 0 -1 -1
0 0 +1 -1
-1 0 0 newest
dependency graph
Keep multiple generationsAcyclic dependency graph
Order-independent evaluation
Implementation : CacheImplementation : Cache
• no full pyramid required, use cache instead
• output determined solely by lowest resolution
AlgorithmAlgorithm
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
evaluate (level=L, row = x, col = y, generation = g)
Cached?evaluate (L, x-1, y, g-1)
2. Collect neighborhood
3. Find best match
1. If in cache, return it
Cache Footprint : Single PixelCache Footprint : Single Pixel
Level 3 Level 2 Level 1 Level 0
Generation 2
Generation 1
Generation 0
Cache Footprint : SCache Footprint : S
Level 3 Level 2 Level 1 Level 0
Generation 2
Generation 1
Generation 0
Cache Footprint : SphereCache Footprint : Sphere
Level 3 Level 2 Level 1 Level 0
Generation 2
Generation 1
Generation 0
Cache Footprint : RandomCache Footprint : Random
Level 3 Level 2 Level 1 Level 0
Generation 2
Generation 1
Generation 0
Cache Footprint: Cache Footprint: Single PixelSingle Pixel
Level 3
Level 2
Level 1
Level 0
Generation 2 Generation 1 Generation 0
1148 pixels!
Cache Footprint:Cache Footprint:Poisson PointsPoisson Points
Level 3
Level 2
Level 1
Level 0
Generation 2 Generation 1 Generation 0
Cache Footprint:Cache Footprint:Circular PatternCircular Pattern
Level 3
Level 2
Level 1
Level 0
Generation 2 Generation 1 Generation 0
Cache Usage StatisticsCache Usage Statistics
Percentage of input requested
Per
cent
age
of c
ache
use
d
random
sphere
ideal (linear)
Cache CoherenceCache Coherence
Quality ComparisonQuality Comparison
old new
QuakeQuake
Texture 64 64 Texture 512 512
Input
44% requested48% computed
QuickTime VRQuickTime VR
Original Result
Input
invisible
Simulation ResultSimulation Result
Architecture DesignArchitecture Design
PitfallsPitfalls
• not feasible for current hardware
• can only be applied to repeating patterns
Finished WorkFinished Work
• Verification using an infinite cache
Ongoing WorkOngoing 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
MotivationMotivation
Texture mapping is important
Texture mapping can be a bottleneck
Solution: Texture Mapping by Synthesis
Hardware TrendHardware Trend
Computation >> Memory Speed
• Transform memory access into computation
![Real-Time Texture Synthesis by Patch-Based Samplingpeople.csail.mit.edu/celiu/pdfs/TOG.pdf · gorithms including Wei and Levoy [2000]. Figure 1 shows an example produced by our algorithm.](https://static.fdocuments.us/doc/165x107/5f96576af4d9283ac6090afd/real-time-texture-synthesis-by-patch-based-gorithms-including-wei-and-levoy-2000.jpg)
