Mark Stock's work on rendering large models w/o ambient cache

Hi Lars,

Many people have tried small -ad settings with the ambient cache, and the universal result is splotchy images. The reason it works when you turn off the ambient cache is that each interreflection calculation varies about the correct value randomly, and looks like noise in the image because it takes up only one pixel (or with downsampling, a fraction of a pixel). Using -aa (anything positive), you spread these high variance values into surrounding pixels, and they look like the measles.



From: "Lars Grobe" <[email protected]>
Date: February 8, 2006 7:09:29 AM PST


Mark did some work on how to get nice results without ambient cache (afaik
he uses -aa .00 -d 6 -ps 1 and downsamples /4 in pfilt). I tried the same on
a very large model, but rendering is slow now because the different views
can't share ambient data. So my suggestion is to keep low -ad and downsample
as proposed, but cache the fewer ambient values in an ambient file using a
moderate -aa. Any comments? I wondered why this was not mentioned in the
studies, am I completely wrong or is it because he simply did not have to
reuse the ambient values (in a comparision with different ambient settings,
that would be a bad idea ;-)?

TIA+CU Lars.