Lighting problems for open world game

Well, as much as I like UE4, the lighting drives me crazy. I am trying to get the lighting set up for an open-world-RPG.

Static lighting isn’t an option because:

  1. I want a Dynamic Day/Night-change.

  2. rebuilding the complete light everytime I move a single object is extremely inefficient.

  3. When there are movable objects, they look pretty out of place.

Simply checking “Force no precomputed lighting” doesn’t look good either:

  1. 19483bf1aea29bcbaba33b56e827629d31226a7d.jpeg

    this seems to randomly appear sometimes, and then again when I restart the editor sometimes it’s gone. I haven’t been able to find a fix for it though. The weird bloom only comes from the movable objects.

  2. I haven’t yet found a way to disable the skylight in interiors, so they are very bright.

Another problem I am experiencing is this one:

e554d6197b7054e76d83d51f13217cf4f27ee6e8.jpeg b09b3287fb1bdc20feaba2a41682f9d80878c451.jpeg This is with “Force no precomputed lighting” checked. But with static lighting it’s still there. Even more noticeable actually.

The cut off light between the tiles isn’t related to the textures. Also it doesn’t only happen with my custom tiles, but even with the standard-walls made by Epic, and on the example-map.

Maybe you have an idea how to fix some of the problems I’m having?

  1. You can use Stationary light dynamically. Bake it once and AFTER bake you can change intensity/color without re-baking.
  2. These glitches at your screenshots looks like bad and power hungry materials. I had same problem when I set Dynamic Material Instance for every object in my game.

Dynamic global illumination solution based on Light Propagation Volumes is available, but it’s still WIP.

Check forums and the link below for some information.

Once you enable Force no precomputed lighting you still have to build your lighting once to get rid of lightmaps.

Thanks for your answers :slight_smile:


  1. That’s not quite what I’m looking for. If I understand you correctly, I would still need to rebuild the complete lighting when moving or adding objects. In smaller levels this may work, but for an open world game, this would comsume massive amounts of time.

  2. It happens with every object (including the ones made by Epic) if they are aren’t static. And I don’t think I set Dynamic Material Instance. The problem must be something else :confused:


I haven’t yet been able to get the dynamic GI to work unfortunately (All it did was tinting some corners yellow and orange ^^), partly because of the weird bloom-bug, but I’ll look into it again.

Any ideas how to fix the bloom-thing?


5fa926825d22cac66b149948607a8acb03afb98d.jpeg This is with bloom turned off.

Does this bloom appear on sample projects as well?

Looks like objects have pretty big emissive values, but since it randomly appears and disappears i don’t think that’s the case.

So far it doesn’t happen on the example-map.

It looks like the issue is with the materials

Unfortunately (despite Epic building Fortnight oddly enough) there doesn’t seem to be much interest left in dynamic lighting solutions for things like a dynamic time of day. Unless this changes, and it well could, I’d… well I’m not sure UE4 would be right for you. :frowning:

Exterior stuff is actually not much of a problem, using the directional light plus LPV will give pretty good results. You have to have well-made content in the first place though.

I’m not sure what you mean by that. I haven’t touched static lighting since Beta. Dynamic lighting will get better as LPV improves and with the new Skylight shadowing in upcoming 4.3.

If I had to guess from just looking at the images, I’d say the blooming/odd color issue is being caused by unclamped colors in the materials and/or light functions. Perhaps posting an image of the material graph might help?

The lighting issue in the second set of images looks like it’s still using the light maps. When you enabled “Force No Precomputed Lighting” did you also rebuild the lighting so that it could get rid of all the maps that had already been rendered?

As for the skylight, at the time being, the only way to get shadowing indoors is to use pre-rendered shadows. This works well with static meshes and a dynamic sun light, but dynamic meshes will not cast skylight shadows. At least not yet.
Dev are still working on dynamic shadows for skylights using distance field AO and will hopefully be ready for the next release.

I’ve had the wierd blooming lights in my current project. I believe it is a bug that has something to do with the number of objects you have in your level/scene. I was able to fix it for now by setting the r.Cache.LightingCacheDimension’ console variable to 128 in the ‘Engine/Config/consolevariables.ini’ file.

There is more infomation and discussion about it in this answer

Hope that helps :slight_smile:

r.Cache.LightingCacheDimension=128 fixed it for the moment, hopefully it’s gone for good this time.

If I understand you all correctly, at the moment it is just not possible to get really good results from completely dynamic lighting. Let’s see whether or not Epic will change that in the future updates. Will this Distance field AO be completely dynamic?

"Will this Distance field AO be completely dynamic? "

Yes, It should be.

"- This type of light supports dynamic scene changes.

  • It gets shadowing from SSAO and a new feature called Distance Field AO.
    The static meshes can be moved at runtime and the AO will update."

Visual quality and performace of skylight DFAO has yet to be seen. If any source users who have grabbed the latest preview would care to enlighten us, that would be awesome.

More info on Distance Field AO + Movable Skylight. It supports dynamic scene changes, static mesh components can be moved around arbitrarily.

It’s not for every project, it has some requirements and limitations.

I’m sorry this is still kicking around, it really should have been fixed by now. I’ll try to see if I can get a fix into 4.3.

Now that the 4.3 Preview is out, I would like to test Distance Field AO. Unfortunately I can’t find a way to activate it…

Edit: Nevermind. My bad.