Issue with Atmospheric Fog and Translucent Materials


I am having an issue with atmospheric fog and translucent materials. I currently have a lake in my scene. This is how it looks when I try and drag out an AF actor:

This is how it looks with just exponential height based fog:

Of course, if I don’t use the height based fog it goes back to normal. I don’t really want to do this though. The level is missing a lot without it. Am I missing something? It also occurs on the glass windows in a building that is in the scene.

Small heads-up: you might want to fix your image links, they are both the same image.

oops. Fixed.

Hi joshezzell -

Take a look at this post, Daniel Wright has provided a good explanation of translucency and fog, here

Thank You

Eric Ketchum

Thank you Eric, but I had already read that posting. None of it actually solves the issue I am having. My translucent materials are setup correctly, the sorting problem occurs once I add atmospheric fog along with exponential height based fog. Once I do that, all of my objects with a translucent material render through the height fog. The only way to make it stop is to remove atmospheric fog. I can’t find anything that explains this. In an outdoor/open world game, these two fog types are both pretty essential.

Hi joshezzell -

After some investigation, I can see that this is in fact a bug. I have entered it in with our engineers and will keep you informed as we progress toward a fix.


Thank You

Eric Ketchum

Any news about this bug? Coz it seems it’s still there right?

Hey gonzamancg -

Our Engineers still have eyes on this issue and are working toward a solution

Thank You

Eric Ketchum

Found a temporary workaround to solve this issue. you just have to create a scene depth mask to add self illumination that uses the same overall color as your atmospheric fog. Will work at great distances up to a certain point.

Any update on this bug?

Hey spinav -

An engineer is assigned to this issue but it is still under investigation, for reference UE-2974.

Thank You

Eric Ketchum

It is now February 2015 (almost March) and this bug still exists. I reported it in July last year. We have a vast island landscape and one of our distant lakes renders right through the fog. It looks horrible.

Hey joshezzell -

Unfortunately this issue is still backlogged, but a developer has been assigned to investigate a fix for it. I wish I had better news to tell you, but I have added a comment to the issue report asking for an update. As soon as I hear anything I will get back to you

Thank You

Eric Ketchum

I noticed that this is issue has been marked as resolved, I wonder if it’s really been resolved? i am still using 4.8 and i am currently being troubled by this particular bug.

Sorry to ask you this again because i could not find information regarding the UE-2974 issue that you have mentioned. But i noticed this in 4.9 changelog:

Fixed missing rendering of some translucent geometry, editor/debug material had SeparateTranslucency on, which often it shouldn’t be.

Was that the fix? I am still a bit reluctant to migrating my project to 4.9, but if this is actually the fix then i will definitely do the migration.


I don’t think it has been fixed yet considering my team still has the problem on all our water bodies in our project, using 4.9.2.

Hello -

No UE-2974 is still backlogged in the system, but I have commented on the post for an update and bumped the community interest.

Still not fixed as of 4.12. Any news?

Two years and still not fixed…

Same here. 4.13 and not fixed yet.

it’s October 2017… on 4.14… as far as I can tell, it’s still not fixed…