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4.21 ExponentialHeightFog and physical lighting

Hi all, first of all let me start by saying that the latest updates in regards to a more physical based approach to lighting are a nice addition to Unreal. :slight_smile:
What I am still struggling with in this new workflow is the ExponentialHeightFog system, which I think needs a small rework.

So for testing purposes, I created a standard sunny mid-day scene. Light source at 120000 lux, EV100 exposure set at 15-16ish. All looks fine.
After that I add the fog. Because the exposure is set so high, the fog inscattering color will basically be pitch black instead of the default blue color.

https://forums.unrealengine.com/filedata/fetch?filedataid=154492&type=thumb

I can fix of course this by mutiplying the color by a high number to get the correct luminance but you have to eyeball it and that just doesn’t really feel intuititive. Basically color picking reverts the range back to 0-1. Where do these numbers even come from? I feel like I’m not really meant to do this. It makes no sense for me to have everything physical accurate, only to ‘having to guess’ the magic numbers for the fog.

https://forums.unrealengine.com/filedata/fetch?filedataid=154493&type=thumb

This is how it looks in unlit mode btw. Totally unworkable if you are actually creating a level and you constantly have to turn of the fog to check unlit.

https://forums.unrealengine.com/filedata/fetch?filedataid=154494&type=thumb

Maybe it would make more sense to have fogging decoupled from exposure values? Or maybe expose a new parameter (fog luminance or whatever) that takes exposure into account?
I don’t really have a straight solution myself so I was wondering what you guys think about this.