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AzureRain
01-15-2009, 01:56 AM
Hi,

Does anyone know of any resources or tutorials for building a hierarchical shadow map? Can't seem to find any online.

Thanks

Jackis
01-15-2009, 06:38 AM
May be, they mean cascaded shadow maps? Or parallel-split shadow maps? Can't figure out, why someone may want to have hierarchical shadows, because hierarchy mean level of details for *the same areas*, and this is shadow map space waist.

AzureRain
01-15-2009, 08:12 AM
Who are "they"? You can read the paper titled "Real time soft shadow mapping by backprojection" to see why someone may want to have hierarchical shadows.

Jackis
01-15-2009, 08:41 AM
AzureRain,

Thank you, I read this paper a while ago. There are no words about hierarchical shadow maps by back-projection. Talking about shadow maps and back-projection is quite a nonsense, because shadow-maps ARE back-projection themselves.

But I know, that there are hierarchical shadow volumes by Timo Aila and Tomas Akenine-Möller - "A Hierarchical Shadow Volume Algorithm", paper can be found here - http://graphics.cs.lth.se/research/shadows/, second from above.

[OOPS]
I got it, what you want. Need to google...
As I understood, the paper you regerenced to is about fuzzy occluded space estimation. This is quite known technique, but it has some limitations. For example, you may see that authors didn't give some distant views with their technique applied, because when you start to improve shadow quality (by some perspective tricks and so on), occluder's size got hard to compute. This is very complex problem and it's written tonns of posts, books and articles on that, and no one can suggest an algo for all needs :(