Got a tree with 23k triangles, how to deal with lightmap?

Hello! I’ve made a tree which I’d like to use in my environment in UE4. The problem is that it’s pretty dense, with 23k triangles that are mostly due to putting a whole bunch of planes with branch-leaf-texture.

First I tried just generating the UVs within the UE4 import dialog. I checked that the lightmap index was set correctly. However, the lightmap just looked like it had many, MANY white dots on it. I imagine this is due to the density of my tree. Also, whenever I baked lighting, I always got an error telling me the tree had overlapping UVs. I also tried cranking the lightmap res up to 1024, with no luck.

Then I tried generating the UVs in Maya, and the lightmap ended up looking like this.


This works without errors, but I feel like I have to crank up the lightmap resolution for it to be lighted properly.

As far as I know, lightmaps shouldn’t have overlapping UVs. Is this how a lightmap for a very dense mesh should look like? Is the solution to just crank up the lightmap resolution? Is a lightmap resolution of 1024 or even 2048 really okay? Or should I just make a less complicated mesh? I just want some pointers on how to deal with huge/dense meshes and lightmaps. Thank you!

Hello JakobBergersen,

You could crank up the lightmap resolution and see an improvement, but if you were to populate your scene with a large number of these meshes you will see a loss in performance. The best way to deal with large meshes like this would be to go into your external modeling program, like 3ds Max or Maya, and break up the mesh on to a couple different UV unwraps. This way your tree body can occupy its own UV space for a more efficient lightmap and higher resolution textures.

Here is some helpful documentation that will give you some good insight on ways to improve the quality and efficiency of your models within the Engine.

FBX Static Mesh Pipeline

Let me know if you still need some more assistance or have any further questions.


Thank you for your answer, that cleared up my mind!