Yes, I think the coincident suns trick should work. Did you try it? It's only valid for distant sources -- anything else would give unreliable results, since local sources cast shadows from one another.
-G > From: Andy McNeil <mcneil.and...@gmail.com> > Subject: Re: [Radiance-dev] direct sampling behavior > Date: September 17, 2015 12:17:09 PM PDT > > Could I test the relative speed by rendering a scene with 64 coincident suns > of 1/64th the radiance? > Actually, if this works, it might be a suitable solution for us picky > penumbra people. > > Andy > > > On Thu, Sep 17, 2015 at 12:08 PM, Gregory J. Ward <gregoryjw...@gmail.com> > wrote: > 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 > > _______________________________________________ > Radiance-dev mailing list > Radiance-dev@radiance-online.org > http://www.radiance-online.org/mailman/listinfo/radiance-dev > > > _______________________________________________ > Radiance-dev mailing list > Radiance-dev@radiance-online.org > http://www.radiance-online.org/mailman/listinfo/radiance-dev
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