Black Mesh Problem

I’ve made four identical interconnecting rooms with decorative wall mouldings. A rectangle of moulding above the door renders correctly on one side of the wall, and black when on the other side (see attached). The problem is the same in all four rooms. When I copy the wall and trim, and paste it into a new level, the problem disappears.

Lightmap UV channel is at 1 and lightmap resolution is 128 for all the moulding meshes. All have the same material applied and all receive much the same light.

Why are these four rectangles alone rendering black? I’m stumped!

Any ideas gratefully received. Thanks!

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For the meshes and all lighting, is Lighting Channel 1 enabled?

Open this optimizing function and check your walls. If they are red or some like that, decrease their lighmap resolution by right clicking on it and edit. If blue increase their lightmap res up to you get the perfect green .Here is numbers of Lighmap res. 32-64-128-256 . Try one of them and get green color.

Very many thanks for the prompt feedback!

presto423 - The meshes are fine, the UVs are well laid out and channel 1 is enabled.

trolltime809 - For light map resolution I’ve followed the advice that what’s good for gaming is not good enough for ArchViz (Ryan Manning tutorial at UE4 Interior Lighting Series (Part 2) - YouTube) – so I’ve pushed densities into orange (see attached). My understanding is that the only downside to higher densities is that they result in longer build times. Have I got that wrong?

I’ve now fixed the problem by replacing the “bad” rectangles with copies of the “good” ones. Why this should work I have no idea! Both good and bad are the same mesh, with the same settings applied. They’re identical. This is what I just don’t get.


Man u have to get that green one. Don’t make higher or lower u have change this color to green.Sometimes it emmits light wrongly İf it is not green. I see this issue on my guns when i use static light.So just adjust them green.

I’d suspect something in the mesh’s settings, not lightmap resolution, to cause it. Or the mesh’s transform values combined with its design (# of vertices, open/closed, subdivisions, etc). If it was lightmap resolution, then why doesn’t it affect the other meshes, and produce light/shadow artifacts on the walls and any other surfaces too?

Does a mesh’s normals and UV lightmap get reconstructed when copying and pasting? or in duplicating? If so, it could be calculating those normals / UVs just enough differently to cause shadowing or lighting error, resulting in black…especially since that copy-paste operation was done on the entire wall/moulding composite.