from .rib file:
# This attempts to show that there are a large number of too bright
# or completely dark pixels when the raytrace hider is used. I have
# attempted to set the bias to 0.01.
This seems to go beyond being a bias issue, since sometimes the pixels are too bright. Using the svn version.
I tried using valgrind with a debug compile of pixie and valgrind claimed to find a number of instances where if statements were based on uninitialized memory. I couldn't track things down much further because I'm not that familiar with the code. Have you ever tried using valgrind? Not all of the errors are worthwhile (the libz and ld errors can be safely ignored), but from my experience the other errors usually are useful to track down.