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Tom York wrote:
> John VanSickle <evi### [at] hotmail com> wrote:
>
>>For animations this is a show-stopper. Picture quality *must* be
>>consistent from frame to frame, and that rules out any perceptible
>>degree of graininess.
>
> I think you can have Maxwell (at least, don't know about the others) cut off
> when a selected noise level is reached.
The only real issue here is whether the noise is really noise or merely
the way the scene is actually supposed to look. I suppose that the best
way to tell from an automated standpoint is to measure subsequent
changes to the pixels, and when those changes are consistently below a
certain threshold, the rendering is assumed to be good enough.
> Animations are possible, but I would
> think the main reason against them would be the crippling render times. When
> one frame can take hours to render, it's really not practical.
For getting stuff out the door quickly, long render times are a
show-stopper, but for a feature film with a five-year production time
table, if your render farm has a thousand boxes in it (such a farm can
be had for less than a megabuck, so the bigger houses can easily afford
them), each box only needs to render 130 to 170 frames; a render time of
half a day is acceptable under those particular circumstances.
> In RAM, they mean? If so, I don't think that can be correct (or up to date);
> look for Ingo Wald's work on out-of-core (and realtime) raytracing. I think
> they must have some use for raytracing or they wouldn't have bothered adding it
> to PRMan 11.
They did; while most reflective surfaces can be simulated well enough
with an environment map (which is how they did reflection before
_Cars_), reflecting objects that are in the scene and which are moving
in the scene require ray tracing in order to achieve the efficiency that
Pixar requires. Pixar trades accuracy for speed when the accuracy is
only going to be noticed by people like CGI hobbyists, but sometimes the
accuracy is discernible by the average Joe, and that's when quality gets
emphasis.
Regards,
John
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