Basic lighting problems ( lightmap) - help!

Hello, thanks for reading this.

I am new to UE4 and a beginner in game developing. I started getting into level design and I have been working in the last week on my first level… a stadium.
I ran into lighting problems from the first stage up until now. I created a stand and then converted it to a static mesh and then multiplied around the field to create the stadium, and the result was getting errors overlapping and unwrapping UVs. Then Tim pointed to me on answerhub ( btw thanks a lot Tim ) about the create unique UV map tool. I did get rid of the errors, but the shadows are still messed up. Then another level designer pointed out that I should be forming the stand out of little meshes, and so I did…a bit better result but still not good.

Then I have found this video explaining how to make UV maps in blender.

All good , the UV maps look better then the ones made with UE4’s generate unique tool but they still don’t work properly.
And the worst part ( that annoys me ) is that after I create a 2nd UV map in blender for this railing and import it into a default fps map it looks perfect when I place it into the level. a761d5f2f870a4bb9a2f2d064e8f8139499e24d7.jpeg
Up until the building light ends. Why is this happening ? I’ve tried changing res , playing with shadow settings…nothing works.

This is how the UV map looks like created in blender and imported with the mesh:

This is the UV map created by generate unique UV tool:

This is how my meshes look like with the override res option set to 256:

I am completely out of ideas on how to proceed and would very much appreciate your help and guidance!

First of all, if you want more detailed shadows on the ground you need to increase the lightmap resolution of your ground mesh, not the shadow casting mesh. The ground in that template map is a BSP brush which means you actually need to use lower lightmap values:

Secondly, the UVs of your mesh are no good for any lightmapping. There’s tons of wasted space, bad aligned edges and too many seams. Should look more like this e.g.:

A lightmass importance volume will also increase the shadow quality on your meshes

On this website you can find common lightproblems + solution:

So both UE4 and blender are useless in creating automated UVs ?

I have followed the exact same steps mentioned here and that was the result.

Nope, blenders uv tool isn’t useless for creating lightmaps-> I have made over 300 meshes with that technique and never got a problem (that’s why I recorded this video) :stuck_out_tongue:

Your problem isn’t the lightmap, you just have to increase the lightmap resolution of your mesh and the ground + add a lightmass importance volume + build the light

I just tried with 128 and then with 512. None of it worked. Are you sure the UV map isn’t just bad like Malkavian said ?


p.s : I am learning right now how to create it manually from

When you have done it in the way I did it in the video it should be fine -> have you already increased the lightmap res. of the ground? (in the static mesh editor)

Ohterwise you could also just send me the file and I will take a look at it

Yes I increased both the ground and the mesh’s lightmap res.
Here is the file : Loading...

These automated algorithms usually fall behind manual work. They might work for certain meshes but mostly you need to place your seams manually to get proper and optimized lightmaps.
UV mapping is a key component of 3d modeling and there is no way to simply skip it.

You shouldn’t advocate bad practice here. The lightmaps UVs shown in the opening post are basically crapp. Increasing lightmap resolution does not solve the issue in the first place which is a bad UV layout.
Why would you use a messy UV layout with too many seams and let’s say a 256²px lightmap if you can get away with a 32²px lightmap and less vertices?

With increasing the lightmap resolution of the ground everything looks fine :smiley:


Yeah, thats true. Do you probably have a good blender tutorial that shows the right way? (just in case that people want to create a good one)

To what extent ? I only went up to 512.

I have set the res. to 512 for the ground mesh and 128 for the railing + this light setup:

-skylight (no shadows)
-lightmass importance volume
-basic template lighting
-I scaled the mesh up so that it fit’s to the scale of the fps template

I created new blank project and it worked like you said, didn’t even had to add lightmass importance volume.

Then I went again into the fps template and used same settings…didn’t work. Then I converted the floor to a static mesh and generated unique UV map for it and this is the result :


I would recommend you to not use any BSP made meshes, because I also got that problem and I had to put the lightmap resolution of the ground to 1024 which is definitely too high. :slight_smile: Use your own meshes instead.


The railing has a lightmap resolution of 32 and the ground mesh 128!

All my meshes are made from bsp(the stands) and I have worked on that like 30 hours. All I can do now is create in maya manual UV maps for each mesh.
But yea …I learned my lesson. For future I will learn how to model in Maya.

Thanks both of you for the help. I’ll update this tomorrow with the results.

Or wait a little bit and probably somebody from epic games or mAlkAv!An will post other solutions :slight_smile:

I’m trying to create my first UV in maya.

Can I connect these pieces together considering they will all be shadowed and pretty much never in then open? ( the stairs mesh will be repeated so that side will never be seen) or is that going to cause bleeding problems ?


Also does it matter if I alternate the shapes a little bit in the UV editor to snap them on the grid?

I would advise against creating everything in your level out of BSP/Geometry meshes. There are a lot of known issues with BSP that can play havoc with your scene. This is one of the bigger reasons why we have Geometry 2.0 on the Roadmap. While it is backlog/wishlist at the moment this is something that will be looked into for future releases.

BSPs are generally used for blocking out a level and getting the playability down before passing off asset creation to an artist. Static meshes are definitely the way to go! :slight_smile:

Since you mention World of Level Design above I won’t rehash that too much.

For the diffuse UV you will want to make sure that your UVs are evenly spaced so that there is no stretching or artifacts.

For the lightmap, adjusting them slightly to fit a grid is not going to be that big of an issue. You can squish or expand them a little and it won’t hurt, within reason of course.

If you have any questions feel free to ask!


Hi Tim, this is what I ended up with :

And this is the result, I am pretty satisfied.

Like I said, this is my first try at creating a level. I’ve done everything using geometry brushes and then applied materials and after I converted them to meshes.
Today I used Maya for the first the time. I’ve seen this workflow in the level design example so I followed it. However I had no idea you should go from brushes to meshes using a 3d software, I thought converting them inside the engine should do it.

If you’ve not seen this yet, it’s worth a watch to see how Epic does it’s level design.

You can open this level in the Content Examples project from Marketplace > Open Map > LevelDesign_workflow.umap

If you’re using simple shapes in UE4 for the BSPs and converting to BSP would probably not be a big issue, but using complex created objects with BSPs and creating meshes out of them will not generate the best results in the engine. Exporting these to a 3d modeling software for reference and editing is probably the best case.

Ultimately, using a 3d modeling software is the best use case. You have complete control of your model and it’s UVs. This is something that cannot be done within UE4.