I don't know of this existing in mental ray, but basically, it sounds
like VRay biases its sample density on the FG map so that the expected
variance of the samples coming from any particular section of the map is
roughly equal. In contrast, if you don't do something like that and you
sample the map evenly, the expected variance from a contrasty area will
be much higher than the expected variance of a low contrast area. To
minimize the total "sum of squares" variance of all the patches added
together (i.e., the random flicker/error of the sampling), you want the
variances of all the light sampled in each direction to be as even as
possible. (Not sure if that's exactly true in a strict mathematical
sense...)
To make an analogy to an FCurve, suppose you have a plotted curve with
tons of keyframes. The curve moves around a whole lot at the beginning
of the animation, then becomes pretty stable at the end. If you want to
reduce the curve to some smaller number of keyframes, you'd want to use
most of them to achieve the contours of the active part of the curve.
And the stable part can be approximated with just a few keys. The FG
thing it's kind of a similar principle.
That said, I've never actually touched V Ray, so I can't say for sure if
that's what they're talking about. If it's not, someone should really
make a shader that does what I just described...
- Andy
Dawa wrote:
Heres the test render for shadows. From V ray.
-Dawa
Dawa Fruitman
Animation director
TOPIX
35 McCaul St., Suite 200, Toronto, ON, M5T 1V7
t 416.971.7711 f 416.971.9277
www.topixfx.com
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*Dawa Fruitman
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*TOPIX
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t 416.971.7711 f 416.971.9277*
*www.topixfx.com*
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