Am 14.12.2010 16:36, schrieb Christian Froeschlin:
> [GDS|Entropy] wrote:
>
>> It has taken 4 days to render 1 pixel that I am now looking at. :(
>
> no slight intended but somehow this statement made my day.
>
> I can just see you admiring the beauty of this one precious pixel ;)

Somehow, this picture must be wrong: POV-Ray 3.7 doesn't output single 
pixels ;-)

> Seriously, I wonder why the texture has such an immense impact
> on your render time. The only cause I can think of is an extreme
> recursion because all your snow and ice stuff is probably reflective
> and irregularily shaped. But that problem would persist even if you
> manage to convert it to a mesh.

But then the intersection test /might/ be faster -- or not. Until he has 
tested it, it's difficult to tell.

Another possible speed killer I see is that - unless I'm missing 
something somewhere - the algorithm for "fusing" the blob textures is as 
follows:

- Look up all the blob elements affecting the given intersection point, 
and add their respective texture & weight to a list (*).

- Walk through the list, computing the effective color at the 
intersection for each single texture independently (includes reflections 
& refractions).

- Compute a weighted average of the effective colors.

Note that if the blob is very "dense", with many blobs affecting any 
given point of the surface, this will give a huge list of textures & 
weights, which is /not/ filtered for duplicates. Such a 
duplicate-removal step at (*) might speed up rendering tremendously.

A mesh-based version with a "baked" "texture weighting map" would not 
suffer the same problem.

Post a reply to this message