Flicker-free global illumination

From Wiki

You are here: mental ray cookbook / flicker-free global illumination

Freezing Final Gather

One trick to get a smooth, flicker-free globally illuminated animation is to freeze the final gather map. For this, you first have mr compute the final gather map once, save it to disk and then just reuse that data for the entire animation. This works best if only the camera and no other object is moving.

Here's the workflow for an "architectural walkthrough", i.e. no moving objects or changing lights

1. set up a FG file, and hit the little "X" to make sure it's cleared out (empty)
2. set your sampling to 1/64 1/64 to render super quick beauty pass
3. render every 20 frames or so (or just render the "representative camera positions"), while writing to the FG file. This will incrementally add to the file as you go.
4. When done, check "Read Only". THIS IS VERY IMPORTANT.
5. Set your sampling back to your "original" value
6. Render your entire sequence

%% what about FG maps and network rendering? %% Zap: apply the mip_render_subset lens shader and give it no subset to render (but check the "render FG for full frame") and get a zero-time main render (but black, of course), without having to muck with your sampling settings.