Lightmap on complex mesh - retopo?

I have a very complex mesh, 1.9million polys, which I lowered to 300k polys in blender by using the “Decimate” modifier. Problem with that is it leaves me with ugly geometry, which I think is badly affecting the UV map and consequently the lightmap. When I build lighting with lightmass in UE4, it leaves me with these ugly triangle shadows. I have tried upping the lightmap res, but I don’t think that’s the source of the problem.

Question is, is a fix here to properly retopologize the mesh? Any other options?

Please refer to pics attached. First pic shows the model after building lighting in UE4. Second pic shows the lightmap view from blender (I don’t think it ideally should look this fragmented, but thanks decimate). Third pic shows the wireframe view of the mesh.

Hi artoculon,

For this type of geometry if you’re insistent on using baked lighting the lightmap that you have laid out will simply not work well. You’ll be left with the artifacts that you’re seeing in the other image.

For lightmaps it’s important to not have any overlapping faces, use the 0,1 space as much as possible, and for a mesh like this to have the pieces connected to get smooth lighting baked across the mesh.

The best thing here to do is to Pelt Map so that the organic rounded shapes can be pulled and laid out without breaking smaller sections off. With Pelt mapping you may need to separate some chunks of the mesh to pelt them properly. So, if we use a human body as an example. I would separate each limb into it’s own chunk that will be pelted. The torso would be split down the sides, waist and neck so that the front and back and be pelted separately.

I hope this gives you an idea where to start.

Tim