I haven't tried any noise reduction yet, but this is where FryRender's selective area rendering comes in handy!
I would just select the caustic area and let it render till its smooth and then let it finish off the rest of the pic
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anyway I did another render - LOL I used a very low res texture on the building, well I still haven't figured out how to tile textures in Indigo
It's been going for a while 7+ hours, 1500+ samples - used v0.9 test2, 1 sample every 10secs...and it's faster than V0.8Stable! Need more CPU grunt
Pure MLT mode with 2x supersampling, Mutation chance 0.1, max mutation change = 0.03. I noticed that when mutation chance was 0.4, the interior glass area took much longer to light up