Very strange, I'll grant you. If you turn off super-sampling (-as 0) or increase -ad to 3000, the artifact mostly disappears. My suspicion is that the method by which the ambient calc estimates errors to decide where to send its super-samples has some regularities due to the hemispherical subdivision I use. Near the inside corners, the visible hemisphere is split into two regions, one of which is much brighter than the other. Moving a small amount left or right causes a large number of divisions to cross over the threshold, which shifts the super-samples and therefore the bias in the calculation.
This bug falls under the category of general shortcomings of the strategies used in ambient sampling, which I hope to largely replace with the Hessian calculation I mentioned in an earlier post. Cheers, -Greg > From: Mark Stock <mst...@umich.edu> > Date: September 3, 2013 7:46:43 PM PDT > > Folks, > > In experimenting with the Turrell piece "Afrum I (White)" I found what > seems to be a bug in the interpolation procedure that becomes notable > for -aa 0. > > Image: http://markjstock.org/transfer/img12.png > Files: http://markjstock.org/transfer/afrum1.tar > > This is with HEAD from today. See the HOWTO file for command-line. > > Mark _______________________________________________ Radiance-dev mailing list Radiance-dev@radiance-online.org http://www.radiance-online.org/mailman/listinfo/radiance-dev
