http://www.pcper.com/article.php?aid=532
John Carmack on id Tech 6, Ray Tracing, Consoles, Physics and more.
裡面提到的sparse voxel octree算是mega texture的geometry版本….
也就是說在rasterizer中”有限度”地應用ray tracer的話,可以做到很有趣的效果。
sparse voxel octree有個好處是,他可以用來把”需要ray tracer的區域分出來,也就是利用區域性。
實際上沒有複雜光源反射的話,ray tracer和Rasterizer相比並沒有優勢….
另外一點是,為了滿足大規模的亂數行為所做的cache model(Larrabee)的實用性也會受到質疑。
觀念上Relief Mapping算是pixel level 的 ray trace,加上sparse voxel octree的話,基本上可以說把ray tracer相對於rasterizer有利的部分都包下來了….
所以sparse voxel octree (IDtech06)的應用可以順利完成的話,應該會比較少單獨使用ray tracer才是。
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補充-Sparse Voxel Octree相關:
http://graphics.pixar.com/IrradianceAtlas/paper.pdf
An Irradiance Atlas for Global Illumination in Complex Production Scenes
Conclusion
We have introduced the brick map, a tiled 3D MIP map format for effcient representation and caching of general surface and volume data. We use the brick map format to improve the photon map method with effcient caching of global illumination irradiance data.
The resulting method enables effcient and flexible computation of multi-bounce global illumination in very complex scenes. It is our hope that this will lead to more widespread use of global illumination in CG movie production.