[Bf-committers] Improving the quality of soft shadows

Ton Roosendaal bf-committers@blender.org
Thu, 18 Dec 2003 14:53:09 +0100


It was one of the first things I tried, getting rid of the annoying  
banding in soft shadow. I didn't get quickly good results with it  
though... the sample patterns I use now need much more research. First  
want to have an optimal one, and then I'll retry. :)

I also want to include in the octree system a method to quickly reject  
rays that don't intersect, based at previous results, or some adaptive  
schedule. That way firing 100 shadow rays can be much faster.

Last note; I think you will like what I am coding now (not committed),  
and that's getting rid of a lot of nasty globals from rendering. The  
main shading loop will be fully made local, accepting an input  and  
output like:

shade(RenderInput *ri, ShadeResult *sr)
and a couple of default helper calls to calculate texture coordinates  
and OSA info.

Which will enable all kinds of nifty stuff later on.


On Wednesday, Dec 17, 2003, at 21:39 Europe/Amsterdam, Nathan Vegdahl  

> I remembered a paper a read a year or so ago that had to do with a new  
> sampling
> stratagey, called "interleaved sampling".
>    I think that it could be applied to the soft-shadow sampling, and I  
> suspect
> that doing so would improve the quality of the soft shadows  
> considerably
> without much expense.
>    (It could also, perhaps, even be incorperated into other  
> over-sampling based
> features in Blender such as anti-aliasing and motion-blur).
>    Here is a link to the paper:
> http://citeseer.nj.nec.com/keller01interleaved.html
> --Nathan Vegdahl
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Ton Roosendaal  Blender Foundation ton@blender.org