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View Full Version : Why do refractive A+D materials get darker as you increase glossy samples?

happychopper
03-18-2009, 02:37 AM
Question...

I'm working on a bottle product shot for a billboard and I'm trying to keep rendertimes down so have been fiddling with my glossy refraction samples but if I increase them from 16 to 32 my liquid material appears to get darker... By the time I'm at 128 samples, the material is positively soupy. All I want to do is drop the samples to increase rendertime whilst I tweak materials - can anyone explain?

ps. I'll chuck in an example pic to explain what I mean in a minute
happychopper
03-18-2009, 02:50 AM
here's the examples... (various same sized regions of a bottle rendered with increasing refraction glossy samples)
MasterZap
03-18-2009, 12:43 PM
The reason is that more rays give each ray lower importance. Then they are likely to go below the cutoff importance in the next interaction. You can change the importance cutoff in the Advanced Rendering Options rollout. Not that it's the "next" hits importance threshold that is relevant, not of the material causing the glossy rays in the 1st place (tho they may be the same, as is probable in this case)

/Z
happychopper
03-18-2009, 04:02 PM
You legend! And to think it was right under my nose, thanks!
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03-18-2009, 04:02 PM
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