Strange Triangle Shadow across meshes

Hi everyone,
Im new to UE4 and i have been trying to build a room. I have successfully managed to import walls and a floor mesh into UE4 from C4D.
The problem is that I get these weird huge triangle shadows (seems to me on the lower right corner of any surface) when I add a light bulb in the room.
If I increase the radius of the bulb the triangles change sizes, but i don’t understand why they would be there…
Any idea on how to fix that?

Any help is appreciated. Thanks in advanced,

Hi,are you using baked lights (change lightmap resolution in world settings\lightmass)?

If you are using dynamic lights maybe UV maps are causing the problem.

But I think is just resolution and put in sky light if you didn’t.


Hey BlueMan!
Thanks for your reply :slight_smile:
I dont know what a baked or dynamic light is. In that case i was only using a lightbulb and a directional light. I did, however, raise the lightmap resolution on the meshes and it improved a lot!
Would you mind posting the average values in general for those parameters? I raised it to 64 but i’m not sure how high i can go (considering Ill only render an apartment)

Again thanks in advanced,

Hi,you can go higher than that.If 64 is too low try 128,256 or 512.I’m not sure if you can go higher than 512.


Hi Seichi,

Lightmap resolutions are meant to be used in power of 2 (ie. 64, 128, 256, etc). Think of these like you would normal textures you would apply to your mesh. While you can use values other than power of 2 I wouldn’t recommend it.

Also, while you can increase the Lightmap Resolution to get better quality shadows, there needs to be a balance between the value you use and maximizing the space in the UVs 0,1 space. For this reason, thinking modularly or at least in breaking your mesh up into separate pieces that are placed in your level would give you much better results with lower lightmap resolutions.

I would recommend the following documentation as a good starting point for understanding some of the key concepts and working with Unreal Engine.

We also have a Lighting Troubleshooting and Tips guide that we setup on our Wiki to help with some of the more common issues with lighting that people run into.

Feel free to ask any questions if you run into any issues along the way or need help. :slight_smile:


Thanks Blueman for the advice and Tim Hubson for the information! Ill go to the park and read everything :smiley: