clipka nous illumina en ce 2009-03-12 14:24 -->
> Warp <war### [at] tagpovrayorg> wrote:
>> clipka <nomail@nomail> wrote:
>>> The "big normals" approach instead uses very large-scale bump maps - e.g. larger
>>> than the whole picture. Multiple sampling is achieved by rendering the shot
>>> multiple times, while the variations in pertubation are generated by
>>> translating the bump map by a (large) random offset. Averaging is done in a
>>> post-processing step.
>>   I think you should read this:
>>
>> http://tag.povray.org/povQandT/languageQandT.html#blurredreflection
> 
> Did already a while ago.
> 
> The averaged textures approach didn't stick though. Maybe because it's *fatal*
> if you have a lot of reflecting surfaces: The rays POV needs to trace will
> explode exponentially with each reflection.
> 
> In contrast, if you do the averaging via multiple renders + post-processing, the
> number of rays is only increased by a constant factor; at each reflection, the
> number of rays multiplies only by the same amount as if the scene used sharp
> reflections.
> 
> If you let adaptive Anti-aliasing do the job, you still can go with a relatively
> low number of rays per pixel in areas that don't have blurred reflective
> surfaces. Let alone that you'll usually use Anti-aliasing (or focal blur) for a
> final shot anyway.
> 
> After the first blurred reflection, there's actually not much benefit in
> multiplying the number of rays even more.
> 
> 
> 
A work around for that problem:
For the objects that have blured reflection, make two copies.
The first one will have the blured reflection AND the no_reflection attribute.
The second will only have normal relfection AND no_image.

That way, the object with blured reflection will not show in the reflections, 
but the one with no_image will.

-- 
Alain
-------------------------------------------------
Congregationalist: Shit that happens to one person is just as good as shit that 
happens to another.

Post a reply to this message