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Something strange is happening at 1 of the corners and on some objects. Lighting problem!


I am having some problems with lighting in my scene.

I am working on my final year project and I keep having problems with lighting. This is the latest one that appeared and I don't know exactly how to fix it.

As it can be seen in the first image, the lighting (I presume the directional one) goes through one of the corners but also on objects that are behind the all and don't tough it. By the way, this happens when I am at a certain distance from them. As I get closer to the place with the problem, it goes away (see image 2), but I am left with some artifacts.

I attached an image with how my walls look like and their UV's for the lightmass (see image 3). # I know that my walls don't have thickness. For that I created a shell (see image 4), that covers the walls and which I can control as I want.

Are my problems there because I don't have a proper thickness for the walls? (If so, should I separate the walls and give each one of them a thickness?) Or can it appear because of something else?



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Product Version: UE 4.13
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asked Nov 02 '16 at 03:20 PM in Using UE4

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avatar image RIPrajanu Nov 02 '16 at 06:46 PM

An update.

I fixed the lighting that was going through the wall on the objects and at the corner. It was the thickness. I ended up separating all the wall and adding some thickness.

However, I did not got rid of some of the artifacts. Can it be because the walls are kinda low poly? Or are my Lightmass UV's done wrong? The way that the UV's are done: The ones on the left (that are snapped to the grid) are the ones for the part of the wall that I will be able to see. While the others, on the right part, no one will be able to see.



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avatar image Tim Hobson ♦♦ STAFF Nov 02 '16 at 09:17 PM

The UVs look ok for this here. Looking at your previous images, the lightmap resolution is set to 32, which seems low for an object this size. This could cause some of the artifacts you see in the corners. Try increasing the lightmap resolution and stopping when you get to a good resolution without artifacts. I wouldn't go too high with resolution if it were for a game, but something more archvis oriented should be OK I think since gameplay isn't the biggest factor vs the render.

avatar image RIPrajanu Nov 03 '16 at 12:23 PM


I left the resolution there at 32 because I use Overridden Light Map Res and increase it's resolution when the object is in the scene (in the Detail box). At the moment is at 512. I will try and go a bit higher. And yes. Is archvis oriented. I might allow the chance to walk in it, as it has to be interactive, but don't think that going higher in rez will effect that.

Thanks for the answer,


avatar image Tim Hobson ♦♦ STAFF Nov 03 '16 at 04:13 PM

For archviz higher lightmap resolutions isn't always a worry.

Looking at your mesh as well you have it intersecting with the other wall that is a separate mesh, or so it appears. If the mesh snaps together you'll get better results than if the mesh is overlapping another mesh.

Some of the white/gray highlights around the floor/corner image look to indicate what I mention above. This can cause light bleed or darkening in these areas. Is that the case for the floor as well that the walls are overlapping it a bit?

For archviz, if you can afford the texture memory, you may also want to try adjusting some of the world settings > Lightmass options for better results too. Static Level Lighting Scale can be lowered, Indirect lighting quality can be boosted but note that you'll want to lower the Indirect Lighting Smoothness as well to get better results. Use the tooltip for suggestions. Lastly, if you can really afford the texture memory using uncompressed lightmaps (very bottom of the world settings > Lightmass section) you can uncheck this, but it will increase texture memory usage for lightmaps by 4x. It may be worth something for you to look and investigate, but use with caution and make sure you're not seeing any performance loss for your target platform with a build.

avatar image RIPrajanu Nov 17 '16 at 02:27 PM


Sorry for the late reply. I did what you suggested in the last post and it worked, I got rid of the artifacts. I just have 1 more question: How can I get my shadows to a better quality? As you can see from the images they are low rez.



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