nemesis nous apporta ses lumieres en ce 2008/01/27 20:20:
> so, any free time in your hands?  want to put that quad core to stress with
> povray 3.7beta?  If you're, try the little scene below.  With +AM2 +A0.04 +J1.0
> 1024X768 on a P4 2.66, it just brought my PC to a crawl for the whole weekend!
> It all began with a challenge in a brazilian forum, when some guy claimed this
> scene:
> http://200.213.105.41/greysilica/exemplos/cjcopojateado.png
> 
> took him 48 hours to render with Blender internal renderer.
> 
> Surely something was wrong, or so I thought.  Well, in the region between the
> bottom of second row cups and the top of first row cups, render time was about
> 11 minutes a line!  It is all about refractions, normals and fresnel
> reflections.  40 hours total on a P4 2.66 with povray 3.6.1...
> 
> I'm sure it's possible to optimize it with some no_image, no_shadow trickery
> with doubles and no_reflection in the main cups, but I didn't thought of it
> beforehand!
> 
You have multiple reflections and refractions. That mean that you have tons of 
rays to compute. Add the aa and the small bumps, you need lot of subsampling = 
lot of time.
Try adding adc_bailout 0.01 in the global_settings.
It will cause a small decrease in quality that can go unnoticed, but will 
accelerate things as the ray tracing will often stop much earlier.

-- 
Alain
-------------------------------------------------
The strongest reason for the people to retain the right to keep and bear
arms is, as a last resort, to protect themselves against tyranny in
government.
Thomas Jefferson

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