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2009-11 Wednesday 25th, Interview spills a lot of secrets and causes amnesia
Thomas Offline
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RE: 2009-11 Wednesday 25th, Interview spills a lot of secrets and causes amnesia

(12-29-2009, 09:24 PM)LargePenguin Wrote: Hi Thomas,

I am interested in this Coherent Hierarchical Culling. Where can I find more information/paper?
is it this: http://www.cg.tuwien.ac.at/research/vr/c...chcull.pdf ?
would be interesting to try it out for a university assignment. In what ways is it better than portal culling?

Do you have your own collision code or do you let newton handle the collision?
Yes, that is it. The algo itself is quite simple and the hardest part is making a good container. For static objects it is fairly simple to do a good kd-tree, but dynamic gets a lot more complex and there is lot of stuff to take into account. Start off with trying to make a static one is my advice Smile

Some pros of the CHC algo are:
- It can be used on just about any sort of environment, but when using portals it only works good in a corridor-room sort of map.
- Even transparent (textures with "holes") textures can add to the culling. So a lot shrubbery will eventually cover to occlude objects.
- No artist set up is needed (lots of this with portals) so it is very simple to work with.
- No long build times like with bsp trees (Except if the object container building is very slow).

Some cons:
- It will never be as fast or as good as something made by a human. With user placed portals there is a lot of tweaking that can be to optimize (remember this also means a lot of hard work)
- When there is too little culled and too occlusion objects checked, it can slow down the rendering instead of speeding it up. There is a lot of tweaking to be done here though and this as a bit to do with how the container is constructed and set up. In other scenes, like viewing an entire city from above where there there are a lot of objects, but little occlusion, some tricks can used.

There is ALOT of stuff to dig into here so I think it would be prefect to do as a university assignment! I spent quite some time with this, but have lots of more things to research and refine.

As for collision, yes, newton is used!
12-30-2009, 10:03 PM

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