How does 'Use camera path' effect auto exposure?

[tmbarker531]

I'm looking for some advice on the best settings for rendering out an animation with as little flickering as possible while using auto exposure. The camera is moving throughout an interior space and at one point the sun animates it's position and the room gets filled with a lot of direct light. It would be helpful to have auto exposure enabled for the animation so the exposure stays correct but in the past when I've enabled it during an animation it's introduced a fair amount of flickering.

Using brute force/light cache, my light cache settings are-
Subdivs: 2000
Retrace: 6
Use camera path: normally I have this checked, but should I turn it off? How does this setting effect auto exposure? If it is checked, how does it calculate different exposure values at different frames?
Type: hash map
Use for glossy rays: unchecked

Thanks in advance for any help!

[^Lele^]

You shouldn't use the camera path option at all.
From defaults (i assume you know how to reset the settings), set the LC subdivs to 3000, the retrace to 8.0, and render.
This is the officially (and strongly!) suggested method to render animations.
Should a few test frames flicker, simply raise a bit subdivs and/or retrace.

Also, make sure you have enough Max AA subdivs (say, 100) to meet the set noise threshold (say, 0.005), lest the image noise level may not be uniform.

Anything which doesn't seem to work as intended with these settings can be treated as a corner case, and we'd be happy to help out with it.

[tmbarker531]

Ok, thanks for the response. What is the point of the camera path option then? We usually set the max aa subdivs lower than 100 (usually to around 40) and the noise threshold much higher than .005 (usually .02) and then use the stand alone denoiser with frame blending. I believe you that the recommended settings would produce a smooth result but the render times would be significantly longer than the settings we're currently using. I guess i'm wondering if there's a work around that would allow for faster render times while still getting a smooth animation in the end.

[^Lele^]

It's old, and there for compatibility with ancient scenes. It's safe to assume it'll go from the UI at some point in the future.

Feel free to keep a quicker setting for renders (and also a lower max AA) if you're going to use the denoiser, as it'll take care of most of the issues by itself.

Will check on our excellent Docs department to see if the animation rendering guide is live already, so that you'll have a bit more to read on this.

[tmbarker531]

Cool, thanks for the info! I think in the tool tip when you hover over the check box you all should add a point about it being an old and outdated option, I always find that really helpful!

[^Lele^]

We have the guide up! you can find it here (at the bottom of the page, the part regarding animation)

[^Lele^]

And Kristin updated a few other pages, you can find them here: https://forums.chaosgroup.com/forum/...-new-tutorials