Reflection Dim Distance Question

[joelly3d]

Is reflection Dim distance an optimization parameter for speed improvements?... or is it more for artistic control?
Curious if it can help speed a scene up. I have a scene with a pile of ice, turns out it is one of the hardest scenes I've ever had to optimize. Takes forever to render because of required Refraction rays. Trying to see what else I can do.
Thoughts appreciated,
-Joel

[mromagnoli]

Dear joelly3d;
The Dim distance parameter avoids reflecting objects that are very distant from the reflective surface. Therefore, you should reduce rendering times, but it may cause problems with representation in reflections. I would recommend giving you a relatively large distance so that important objects are not lost in your reflexes.
regards

[dgruwier]

As for optimizing your shader, you haven't already tried it you can try reducing the reflections and refractions max depth on the shader, and/or try overriding the base shader with a simpler diffuse shader. It might not look right depending on exactly how the shader looks, but under the right conditions you can cut render times in half without any major artifacts.

[joelly3d]

Yeah unfortunately it is ice. Lots of ice on top of each other too, so if I cut refractions it is way faster, but makes the ice turn super muddy looking. About 10 is the minimum I can cut it to without pooing it up. It's very intersting because I have had rendered 50M polygon scenes faster before, but calculating multiple refractive ice surfaces together just makes it all as slow as time at the edge of an event horizon.

I may just let it go and deal with it. Short sequence so I can afford it for now.