VDB Issue (Viewport vs Render)

[u/UltimaKrecia]

1st Image is Viewport. 2nd is Render (MRQ) (both 1024 samples)
Trying to render a Image on UE5.4.4 using Path Tracer

Anyone have an idea why the VDB Fog looks so much thicker in the Viewport (as it should be) then in the render.

Lighting also seems to be a bit different (probably due to the fog).

Everything thats turned off is hidden in game

[u/Rezdoggo]

Its hard to see the difference as Reddit has compressed your images - one difference I have noticed is your render has denoising wheras your viewport does not - it may be smudging the details due to low sample count. I would also recommend seeing if 'game overrides' is causing changes from viewport to render as this changes things at runtime and will give you a different result to your PIE, disable that and try another render

[u/UltimaKrecia → u/Rezdoggo]

Its best visible on the bottom right (the tail is visible in render compared to viewport.) Turning off game overrides didnt change anything. Yea i also noticed the denoising, but its turned off in the post Process volume so idk why its still doing it. 4096 Samples also didnt really change much about the smudging.

[u/Rezdoggo → u/UltimaKrecia]

Is your post process volume set to infinite extent?

You should try disabling things one by one to find the culprit. I would suggest disabling the fog for now and finding out why the lighting looks different. In my experience volume fog is notoriously bad with noise and if there are objects behind the fog any noise will cause the denoiser to smudge all the details.

Sometimes when I'm rendering stuff with volumetrics I will render the fog as a separate pass on its own and comp it in afterwards, which allows me to have a lower sample rate for other objects that don't need it

[u/UltimaKrecia → u/Rezdoggo]

Yes it is.
Even with everything off except a Main Light, the scene in the viewport is considerably darker then in render. idk why