Stefan Roettger, VIS Group, University of Stuttgart

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The Terrain Rendering Pipelinewww.massive.de

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Intro

• In interactive entertainment terrain rendering is
  much more than the display of a height field.
• Without additional FX the terrain would just look
  incredibly boring.

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DX7 vs. DX8
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Outline of the Talk

• How to handle lots of FX conveniently?
• The complete task of terrain rendering can be
  organized as a pipeline!
• For each stage of this pipeline we present a
  state of the art example from the actual DX8 game
  AquaNox.

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Stage 1 Terrain

• Terrain defined by height field
• Size 2049 x 2049 ? Triangles 8 M
• Use C-LOD terrain renderer to reduce triangle
  count to lt 10 K Roettger '98
• View-dependent triangulation ? Apply geomorphing
  to prevent popping
• Update every 10 frames for reduced load

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Stage 2 Textures

• World texture is splatted on the terrain ? Coarse
  color information.
• Depending on material properties a fine material
  texture is blended over the world texture ?
  Impression of structure.
• Very fine detail texture adds variance to the
  material texture in the near vicinity (greyscale
  texture for maximum resolution).

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World Texture
Material Texture
Detail Texture
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Stage 3 Lighting

• Normal map used for illumination since per-vertex
  lighting is infeasible.
• Dynamic caustic map

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Stage 3 Local Lights

• Besides global illumination, for each frame the
  footprints of up to 500 dynamic local lights are
  rendered into a hires light map.
• Shadows on the ground and objects are implemented
  by a comparison of object height and light source
  height which is coded into the alpha channel.

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Stage 4 Organic FX

• Plankton drift is simulated in vertex shader.
• Plants are placed randomly based on a
  distribution map (mainly vertex shader).
• Buildings are simply placed into the ground.
• Caves are modeled by entrance geometry which
  resides on a transparent spot.

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Stage 5 Volume FX

• Layered Fog Heidrich '99
• Density of fog is a function of height.
• Pre-integrated lookup texture for exponential
  attenuation.

Z (viewer)
Distance (vertex)
64x64
DZ (vertex viewer)
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Fog
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Fog
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Conclusion

• In summary the presented terrain rendering
  pipeline applies a single texture map for each FX
  stage ? Multi-pass approach.
• Fast rendering through multi-texturing.
• Scales well on different graphics adaptors.
• Ease of implementation by separation of FX.

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Preview of AquaNox 2

• Questions?

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• Even more questions?

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• www.massive.de
• www.informatik.uni-stuttgart.de/roettger/
• Thanx!