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Cone Tracing and Path Tracing - differences.

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Hi.
I'm trying to implement this technique: http://blog.icare3d....tion-using.html
The paper about it isn't detailed and it's missing some info.
I did research about voxels, I found technique for fast voxelization. But still, I don't know about cone tracing. There are no papers about this technique. I know the basic difference between path tracing and cone tracing. The difference is that you trace cones instead of rays. So instead of shooting hundreds of rays, you just shoot few cones. But still, I'm missing a lot of informations about this technique to implement it. Can somebody explain me cone tracing? Or give me link to paper. I WAS using google. I found nothing. All I found is undetailed wiki page about cone tracing. Thanks in advance. Sorry for my poor english. Edited by MrOMGWTF

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In cone tracing you sample a prefiltered geometry. (mipmaps)

Depending on radius of cone change to lower mipmap, thus when it hits you get sum of all information in the smaller voxels down the mipmap tree.
This is the reason you do not need to shoot so many rays/cones this way.

Older papers give more information on their cone-tracing..
http://www.icare3d.org/research-cat/publications/beyond-triangles-gigavoxels-effects-in-video-games.html

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In cone tracing you sample a prefiltered geometry. (mipmaps)

Depending on radius of cone change to lower mipmap, thus when it hits you get sum of all information in the smaller voxels down the mipmap tree.
This is the reason you do not need to shoot so many rays/cones this way.

Older papers give more information on their cone-tracing..
http://www.icare3d.o...ideo-games.html


Is it possible to do cone tracing on polygons? Edited by MrOMGWTF

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Cone tracing of polygons is possible...but beam/cone tracing is quite different when using polygons.
Voxels simply make it easy as they are easily prefilterable, polygons are not.

Easiest way to get it to work with polygons is to voxelize them and use voxel cone tracing.. (which is apparently what Unreal Engine 4 does.)

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Oh, I have another question. If a cone intersects a voxel, then were is the hit point? Ray has no thickness, so it hits in one point, but cone has volume. Edited by MrOMGWTF

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The paper about it isn't detailed and it's missing some info.
just FYI, the first part relating to the voxelization was released as a free chapter from the OpenGL Insights book, you can find it here (according to Cressin's Twitter page, the full source will be released soon, probably to the git repo here).

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[quote name='MrOMGWTF' timestamp='1343301831' post='4963254']
The paper about it isn't detailed and it's missing some info.
just FYI, the first part relating to the voxelization was released as a free chapter from the OpenGL Insights book, you can find it here (according to Cressin's Twitter page, the full source will be released soon, probably to the git repo here).
[/quote]

I know how to do fast voxelization. I'm looking for info about cone tracing.

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Oh, I have another question. If a cone intersects a voxel, then were is the hit point? Ray has no thickness, so it hits in one point, but cone has volume.

I'm quite sure that cone size is byproduct of mipmaps, voxels get bigger so basically ray gets 'volume' as well.

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Paper's at http://maverick.inria.fr/Publications/2011/CNSGE11b/index.php

Seems extremely tricky to implement well.

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Well, I was trying hard, but my 13 years old brain can't handle cone tracing.
Do you know any other, easy to implement, real time global illumination techniques?

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