Scaling auto exposure?

Is there a way to scale the auto exposure? In other words, is there a way to apply a scale factor to the exposure level? For example, the scene thinks the brightness should be at +6, but given say a 50% scale factor, it only sets the scene to +3. The reason for this is that there are times when you want an area of a map to be dimly lit for mood. But the auto exposure defeats it. It would be nice if there is a way to scale back the effect.

Configs of the auto exposure can be changed via a post processing volume. Just place one on the map and change the settings as you want.

Unfortunately, there’s no control in the PPV to do what I’m asking. What I’m looking for is a gain control on the auto exposure. (Even better would be the ability to assign a curve to it.)

This is a really rad approach to localized tonemapping that would make some of the auto-exposure issues a bit easier to deal with:

I haven’t gotten around to implementing it in any form yet, but it’s theoretically possible to write a post material that is specified to replace the tonemapper and work from there.

Also, the “View HDR” view mode is critical for just ensuring your scene is balanced in the first place. For instance, I did a pass on normalizing the intensities in my scene the other day because this is where it was in a night (dark) state:

Notice how the majority of the luminance values are all well below the range of the tonemapper. That’s basically just a nightmare, but with a (non-trivial amount of) work you can find a good balance.

The setting you want is exposure bias. It will take the output of the auto exposure system and then multiply it by whatever number of F stops (-1 = half brightness, etc). You can find it in the post process volume.