Placed into my level, all is good WITHOUT a lightmap on the object:
As soon as I build lighting, the object turns dark, but some parts are still bright:
It gets even weirder when I place the object into the starter content map “Advanced Lighting”. With the lightmap built, parts of the object turn black…
…but strangely NOT on the sunlit side!
Here are my lightmap UVs. Not an ideal layout, but I can’t see anything that explains that behavior:
What lightmap resolution are you using? Try looking at the model after you bake it with just a grey basecolor? The model doesn’t seem designed very well for having baked lighting, could you post a wireframe screen shot?
Thanks for looking, darthviper and Zac. Reflection probes are in place, I even tried a few more around the object to see if they make any difference (they didn’t). The whole object has metallic properties, but strangely only parts of it go dark.
I tried lightmap resolutions of 64, 256, 512 and 1024 - didn’t make a difference, except that more was black with the 64 lightmap if I remember correctly. I will try a bake on grey basecolor tomorrow, great idea!
For something that is baked, you ideally want as few UV islands and floating parts as possible. I’m not saying it needs to be water tight, or have no floating details, but instead of having dozens of parts, try to keep it under a dozen.
OK, turns out that the UE4 automatic lightmap UV unwrapper indeed produced that error, although the unwrap seemed alright at first glance. What really threw me off was the fact that things looked fine in the “sunlight”. Changing the viewport to “Lightmap Density” was helpful in seeing that something is off - I should’ve thought of that earlier. I provided a second UV channel with a manual unwrap and all is now fine.
