SH Lightmap: Precomputed GI

Parameterized all scene into huge 2D lightmap atlas

Lightmap density

  • Low-poly proxy geometry
  • Fewer UV charts/islands
  • Fewer lightmap texels are wasted

Using offline lighting farm to calculate irradiance probes for all surface points

Indirect lighting, final geometry

  • Project lightmap from proxies to all LODs
  • Apply mesh details
  • Add short-range, high￾frequency lighting detail by HBAO

Lightmap: Lighting + Direct Lighting

Direct + indirect lighting,final geometry

  • Compute direct lighting dynamically

Compress those irradiance probes into SH coefficients

Store SH coefficients into 2D atlas lightmap textures

Final Shading with Materials

Final frame

  • Combined with materials

Lightmap 总结

  • Pros
    • Very efficient on runtime
    • Bake a lot of fine details of GI on environment
  • Cons
    • Long and expensive precomputation (lightmap farm)
    • Only can handle static scene and static light
    • Storage cost on package and GPU

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https://caterpillarstudygroup.github.io/GAMES101_mdbook/