1. Perfect Spatial Hashing
Sylvain Lefebvre Hugues Hoppe (Microsoft Research)
We design a perfect hash function to losslessly pack sparse data while retaining efficient random access:
Hash table
Offset table
Hash table
Offset table
1282
382
182
1283
353
193
Hash function
Applications 2D 3D
Simply:
(modulo table sizes)
Offset table 
24372
11632
83333
453
Hash table H
3D textures
3D painting
Domain
10243, 46MB, 530fps
20483, 56MB, 200fps
Vector images
Sprite maps
nearest: 7.5MB, 370fps
10242, 500KB, 700fps
+900KB, 200fps
Perfect hash on multidimensional data
No collisions  ideal for GPU
Single lookup into a small offset table
Offsets only ~4 bits per defined data
Access only ~4 instructions on GPU
Optimized spatial coherence
1.8%
Simulation
Collision detection
Alpha compression
2563, 100fps
10243, 12MB, 140fps
0.9bits/pixel, 800fps