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Rendering Forest Scenes in Real-Time

Rendering Forest Scenes in Real-Time. Philippe Decaudin Fabrice Neyret GRAVIR/IMAG-INRIA, Grenoble, France. EGSR 2004. Rendering Forest Scenes in Real-Time: Previous work. Billboards Textured quad facing camera, or cross Widely used by applications Flight simulators, Games, …

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Rendering Forest Scenes in Real-Time

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  1. Rendering Forest Scenes in Real-Time Philippe Decaudin Fabrice NeyretGRAVIR/IMAG-INRIA, Grenoble, France EGSR 2004

  2. Rendering Forest Scenes in Real-Time:Previous work • Billboards • Textured quad facing camera,or cross • Widely used by applications Flight simulators, Games, … + efficiency - no parallax, popping • Simplified textured trees + parallax, 3D consistency - more expensive Rendering Forest Scenes in Real-Time

  3. Rendering Forest Scenes in Real-Time:Previous work • Points • Objects = distribution of discs [Levoy, Whitted - 85] [Pfister et al - SIG’00] [Rusinkiewicz et al - SIG’00] [Stamminger, Drettakis - EWR’01] [Dachsbacher et al - SIG’03] … + adaptive - aliasing (-) cost = 1 transformed vertex / point [Stamminger Drettakis 01] Rendering Forest Scenes in Real-Time

  4. pattern Rendering Forest Scenes in Real-Time:Previous work • Volumetric textures • Volumetric densities to represent fuzzy material [Kajiya, Kay - SIG’89] [Neyret - GI’95TVCG’98] [Meyer, Neyret - EWR’98] [Lengyel et al - EWR’01] … + few polygons, more textures + easy to filter - repetitive tiling - slicing might be visible Rendering Forest Scenes in Real-Time

  5. Our approach • Goal: • Render dense forests • In real-time • With good visual quality • Smooth during a flyover Assumption: forests are viewed from a distance • Approach: improved real-time volumetric textures • Avoid pattern mapping repetition • Avoid view dependant artifacts • Adapted to the distance Rendering Forest Scenes in Real-Time

  6. [Stam - 97] [Neyret, Cani - SIG’99] [Cohen et al - SIG’03] 1. Making volumetric texture aperiodic • Aperiodic mapping • Avoids repetitivity • Requires a set of edge-compatible patterns Rendering Forest Scenes in Real-Time

  7. v u 1. Making volumetric texture aperiodic • Storing the patterns Hardware friendly + one texture + wrap + compliant withmin and mag filtering Rendering Forest Scenes in Real-Time

  8. 1. Making volumetric texture aperiodic • Shape of a forest pattern: a prism • We build a set of edge-compatible prisms, that we call Texcells Rendering Forest Scenes in Real-Time

  9. 2. Our slicing scheme • Volumetric data cannot be rendered directly by GPU • Rendered using textured slices • The simplest slicing scheme: • Slices parallel to the terrain • But suffer from artifacts… Texcell Slices Terrain Rendering Forest Scenes in Real-Time

  10. Slicing is visible at grazing angles  LOD Too blurred Too transparent 2. Our slicing scheme • Slices parallel to the terrain : artifacts  Silhouette texcells  Anisotropic filtering  Opacity adjustment Rendering Forest Scenes in Real-Time

  11. Regular texcells • Sliced parallel to the ground • Set of 2D textures • Good quality and efficiencyexcept at the silhouette • Silhouette texcells • Sliced "parallel" to the screen • 3D texture • More expensive usednear the landscape silhouette 2. Our slicing scheme • 2 kinds of texcells Rendering Forest Scenes in Real-Time

  12. 2. Our slicing scheme: silhouette texcells • Tilting the slices • Vertices are moved vertically, no new vertices are created • Can be done by a vertex program Rendering Forest Scenes in Real-Time

  13. For regular texcells • Texture set: 2D textures + MIP-map 3. LOD scheme • For silhouette texcells • We fit the slicing rate to the MIP-map level of the 3D texture Rendering Forest Scenes in Real-Time

  14. Results • Texcells: • 128 slices of 256x256 textures 12 Mb of compressed texture • 20 trees / texture • Aperiodically mapped • Shading • precomputed and stored in the textures • + pseudo-shading corresponding to the lighting of the terrain Rendering Forest Scenes in Real-Time

  15. Seq #1 • ~2300 trees • 570 texcellswith 4 trees/texcell • ~30 fps 640x480(P4 1.7GHz, GeForceFX 5800) Seq #2 • ~37000 trees • 9200 texcellswith 4 trees/texcell • ~20 fps 640x480(P4 1.7GHz,GeForceFX 5800) Results Rendering Forest Scenes in Real-Time

  16. Conclusion & future work • A scheme for quality real-time volumetric textures • Coupled with an aperiodic mapping scheme • Correct filtering of the volumetric data • Full parallax effects • Well suited to represent and render dense forests • Texcells can be mixed with other representations Future work • Better culling • Dynamic lighting and shadowing [Poster at Siggraph 2004] • Maximize the use of the GPU Rendering Forest Scenes in Real-Time

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