Perfect Spatial Hashing

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
382
182
1283
1282
353
193
Applications
Hash function
2D
3D

• Simply

(modulo table sizes)
Offsettable ?
24372
11632
833?33
453
3D textures
3D painting
Hashtable H
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
10243, 12MB, 140fps
2563, 100fps
0.9bits/pixel, 800fps