> Darren New wrote:
>> Color me unimpressed. Maybe it's because I'm not an expert, but some 
>> of the sub-surface scattering stuff is the only stuff that looks 
>> particularly good to me. Balanced against most of their proud gallery 
>> being obnoxiously grainy, I don't see it as a win just from the photos.
>>
>> Is it possible to automatically know when a scene is good enough? Or 
>> does it take human intervention to say "ok, stop now and move on to 
>> the next frame"?
> 
> 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.  Letting the unbiased renderers go until the grain 
> is gone is not practical, because that requires a human to monitor the 
> render, and requires that human to decide consistently from one frame to 
> the next.  The only way an unbiased renderer could be used in animation 
> work is to let it render the first frame of every shot, decide on an 
> acceptable quality level, and then allow that much time for each frame, 
> and hope that the movement of some object or the camera doesn't increase 
> the time requirement significantly.
> 
You can always process more later. I played with an open-source 
forwards-raytracer (not sure if it's really unbiased) where you could 
save data to a file, and at any moment reload it and render some more. 
You could also start up instances on different computers, let them run 
for a few hours/days, and then merge the results.

So it would be possible to render up to a certain quality level for all 
frames, then (in some automated way) reload each frame, render a few 
more passes on them, and save them back. Or, render only one pass on 
each frame, so that you get the whole animation done pretty fast (even 
though it would be EXTREMELY grainy), and then repeatedly render single 
passes on all frames. That way all frames would slowly get better at the 
same rate.

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