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On Fri, 29 Jan 1999 10:01:06 -0500, Nathan Kopp <Nat### [at] Kopp com> wrote:
>My current implementatin uses mean-split balancing instead of median-
>split. This saves time during the balancing phase (no full-fledged
>sorting required), but requires a little bit more memory (although
>not more than than ranger). With the median-split, you don't really
>need left/right pointers in the tree... searching the tree is like
>doing a binary search on an array.
The code I sent you does median-split balancing without doing a full
sort at each phase, and I think finding the median of a group of points
is still O(n). Don't ask me to explain the algorithm, though. I just
got Knuth for Christmas and I haven't gotten that far yet. :) The end
result is that each leaf node is actually fairly unsorted.
>Jensen has a paper on this topic called "Importance Driven Path Tracing
>using the Photon Map". From what it sounds like in the paper, he still
>has to sample rays fro diffuse surfaces, but the photon map just adds
>appropriate importance to directions of higher contribution.
That's an older paper. While it has some good ideas that you need to
know when you get to the later papers, the actual technique he uses
in the later paper is vastly different than just firing a few rays.
Unless I completely misread it, that is. :)
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