View Full Version : Day to Night mia_physical sky and FG

09 September 2011, 08:59 AM
I've hit a brick wall. I have an interior scene with mia_physical sky that I have animated the directional light some from frame 1-120. It's a transition from daylight at frame 1 to a darker contrast at frame 120 where the sunlight recedes.

What I have done is 1 render at frame 1 and off on the other frames. The transition is not right and the shadows look like crap, it's not smooth. The map basically try's to read the render from frame 1 throughout and this causes issues since the lighting is darker on latter frames.

I have seen videos across the net where people have done this transition with no flicker. How in the hell do you do this with a final gather map, is my question. I have spent more time on this than I should so I'm asking out desperately for help. Please, someone inform me how lighting changes like this can be done with final gather.

09 September 2011, 07:04 PM
One thing you can try is to reverse all the keys in your scene and start the rendering from the darkest to the lightest, this way the FG map gets built up as you add more light.


09 September 2011, 08:45 PM
Well... that would require fg on freeze mode, but I'm not sure it would work with a stationary camera, I would expect it to say it has already calculated the fg for that point and reuse the prior calculation.

I think you'll have to use rebuild on to recreate the fg for each frame. You'll get your shadows right. I guess you are already using portal lights. The problem you might get is FG flicker. If you get problems with that read up on flicker free fg with mental ray. There are a lot of threads about that already.

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09 September 2011, 08:45 PM
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