[Bf-committers] Does Cycles waste half it's possible performance or am i wrong?
Tobias Oelgarte
tobias.oelgarte at googlemail.com
Sun Oct 28 18:27:53 CET 2012
I uploaded a small illustration for my example and to illustrate the
worst possible scenario for box filtering. I made the following
assumptions for the worst case:
1. Despite normally random distribution all pixels are sampled at the
right side, which would be even possible, but very seldom.
2. For the top left grid i made the assumption that every odd sample
would return 1 and anything else 0, also possible and seldom. It also
illustrates how the image would look in Cycles for this case.
3. For the bottom right grid i used area averaging, despite same odd
sampling situation.
The implication of this sketch is, that the noise for 1 pass would not
be reduced by Cycles. But if we would average the samples like in the
bottom left illustration it would be divided by a factor of infinity,
resulting in 0 for this special case and in factor 2 in average for a
truly random distribution, since a sample would affect 2 pixels at a
time in average. I i had chosen the grid intersections, to make it even
worse, then this would be even a factor of 4, since four samples would
contribute to a single pixel.
http://www.pasteall.org/pic/39642
Greetings Tobias
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