clipka wrote:
> Some things to note here:
> 
> - Radiosity probably does not contribute very much to your scene. You 
> have lots of reflective surfaces, and the others are quite dim. There is 
> not much diffuse interreflection going on here, so quality on that is 
> probably not an issue.
> 
> - error_bound 0.2 is insanely low.
> 
> - make it a habit to always set "always sample" to "off". It really 
> doesn't help at all (except if you want to provoke artifacts).
> 
> - recursion_limit does /not/ specify the "max_trace_level" to use for 
> radiosity sampling rays. Instead, it solely governs whether 
> radiosity-based illumination will be taken into account recursively, and 
> to what depth. Aside from that, radiosity sampling rays are treated 
> pretty much like normal rays, i.e. the number of classic reflections 
> they will follow is governed by the global "max_trace_level" (with some 
> caveats, but that's a different story). Given that radiosity probably 
> contributes very few to your scene anyway, the "radiosity effect on 
> radiosity" will be pretty close to zero, so you can set this value to 1.
> 
> As a matter of fact, radiosity contribution is probably so low that this 
> is one of the very few scenes where I'd personally try to go completely 
> without.

Fixed the error bound (I used 0.2 as a start because it was used in 
Bill's test scene for the solids), which did speed up the render.
I am using radiosity because I'm lighting with a HDR probe, and the 
black 'bonds' in the structures are very dark without it.

Here's another version - The render time dropped to just over 1 hour, it 
would have been even faster but I bumped up the focal blur samples to 70 
instead of 20, which made a visible improvement for me. Recursion_limit 
was decreased to 1, and error_bound went up to 0.8. Even with 
'always_sample off' I see in the message window that there is a line for 
the 'Final' radiosity pass that has just over half of the total samples 
taken, is this the actual final render pass or just the last radiosity 
pass before the final trace?

Post a reply to this message

Attachments:
Download 'buckyballs_red.jpg' (203 KB)

Preview of image 'buckyballs_red.jpg'