Can someone who has run the POVRAY code confirm that a full 50 iterations were used? I ask because if you look at the image on the Paul Bourke site (image d in the attachment here), there is a hole in the middle, relative to the comparable frame from the animation (image b ). I coded it up myself in matlab to get an independent assessment, and the hole is there if more than 12 iterations are run (image f), whereas the image looks right if not enough iterations are run, say 12 or less (image e). The example in the POVRAY documentation suggests 8 iterations, with 20 as a default... Youngy, skaaa, and Kari-no-sugata all appear to have downloaded POVRAY so if one of you can confirm this I'd appreciate it.
Side note: my images don't match perfectly partly because it was hard to get the perspective to match POVRAY and partly because POVRAY cheats and doesn't check every point, but rather makes a few assumptions and approximations to speed up the computation, but I rotated the images in 3d and the perspective issue doesn't seem to account for the discrepancy.