Dear Picky Penumbra People (Andy): It's difficult to say for sure without implementing such an option, but the source sampling often dominates the calculation time to the point where you might not gain much over your current approach. Increasing image resolution adds some minor costs for the initial ray casting from the view point, and some calculation time looking up and interpolating values from the ambient cache (assuming you are using that), but those are pretty nominal. Your biggest gains for multiple source sampling would come from scenes with only one or two light sources.
One thing to bear in mind is that lights that are either sphere or source types don't know how to subdivide, so the -ds option doesn't do what it should for those emitters. Otherwise, you can get better penumbras by reducing your -ds value to some small (non-zero) value in addition to using -dj 1. Cheers, -Greg > From: Andy McNeil <mcneil.and...@gmail.com> > Subject: [Radiance-dev] direct sampling behavior > Date: September 17, 2015 11:04:22 AM PDT > > Hi Radiance Developers (Greg), > > I often find myself oversampling an image by as much as 8 times to render > smooth penumbras. I wonder if it would make sense to add an option to > Radiance that would allow users to force additional direct samples when they > want nice penumbras (assuming that -dj is non-zero). Then when I want a final > image that is 1200x800 I don't need to render it at 9600x6400 and filter it > down, I could render at 1200x800 and request 64 direct samples per light > source to get the same smooth penumbras. > > Would this actually help me, or is the time difference between rendering > 9600x6400 with 1 direct sample to rendering 1200x800 with 64 direct samples > negligible? > > Andy
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