Geometry Clipmaps Efficient Rendering of Large Terrains Frank

Geometry Clipmaps: Efficient Rendering of Large Terrains Frank Losasso Hugues Hoppe Microsoft Research Explore Mars Explore the United States Mount Rainier Gusev Crater Ma'adim Vallis Olympic Mountains Conterminous 48 states at 30 m spacing (216, 000 93, 600 = 20 G samples) [from US Geological Survey (USGS)] compressed from 40 GB to 350 MB Challenges: Full planet at 128 samples/degree (46, 080 22, 528 = 1 G samples) [from Mars Orbital Laser Altimeter (MOLA) of Mars Global Surveyor] compressed from 2 GB to 23 MB Other benefits: • Concise storage (within system memory) • Fast rendering (60 frames/sec) • Visual continuity (no pops) Solution: geometry clipmaps: • Store terrain as a compressed image pyramid (100 x savings) • Render nested regular grids about the viewer • Blend the grid levels using transition regions (fast GPU programs) Optimal triangle strips; batched primitives 60 M /sec Efficient view-frustum culling ~3 X speedup Incrementally computed normal maps inexpensive shading A very coarse geometry clipmap Transition regions (blue), As the viewer moves, the clipmap is incrementally refilled using either: • regionally decompressed terrain (PTC image decoder) or • fractal synthesis (to invent detail at infinite resolution) It’s all done on-the-fly Same LOD framework on textures seamless, tile-free texturing and z-based coloring Zero detail Synthesized detail Runtime geometry amplification “free” detail Applications: Flight. Sim, MMORPG, Map. Point, Atlas, Terra. Server, …