No problem about that attaching of images. I’ve seen it before, and had a problem too. Which option is better, the attach or insert? I think insert won’t double post, but be careful of its’ sizing.
There’s definitely overlap in the first UV chart. The second one looks great overall, but the spacing might be a bit too much…although it’s quite evenly spaced. I think you’re correct about edge loops and the Blender smart UV method and also the UE4 changing UVs by default. There’s the option to maintain UVs on import, or to generate new ones via the auto-generator built into the engine (which is accessible in the Static Mesh Editor). I’d suggest 3-4 more edge loops on the long cylinder part of the columns, and perhaps 1 or 2 extra edge loops at the transitional areas too (transitioning from one diameter to a bit larger diameter, and then a curving slope to the square top structure. In the picture, the one edge loop about 1/3 up the column roughly corresponds to the height the incorrect shadowing reaches. And it’s probably also corresponding to the 1st UV chart, where there’s a ton of overlap in the middle / middle-left area. Lots of overlapping UVs in the right area too. Try shrinking the UVs in the 1st chart in order to space them out and remove the overlapping entirely. Adding a few more edge loops to the columns might make it easier to separate the UV islands / pieces and remove that overlap.
As for the Blender Smart UV thing, skip it. Re-work the UVs before exporting, and then ensure that UE4 is set to preserve the imported UVs. Look that up in the docs for how to do it. It’s somewhere in the main lightmaps / UVs pages. I’m working with dynamic lighting mostly now, but recall a ton of reading I did in the forums and docs regarding UVs and lightmaps. They’re tricky, that’s for sure. Several rules about lightmaps and UVs, particularly in reference to UE4, are as follows:
- No overlapping UVs
- Size of UV islands (pieces of the mesh flattened to fit in the lightmap) can be decreased or increased in the chart, but try to utilize the 0-1 UV space by not having huge gaps between the islands, and also not letting the islands go off the edge of the chart. Since you’re maintaining the UVs from Blender / external app, and not using UE’s built-in auto-generator, create at least a 1 pixel wide margin for the UV lightmap chart. No UVs / islands / pieces should be crossing over that margin at all.
- Cut up the islands into smaller pieces if necessary, but in such a way that it correlates to the structure of the mesh and the intended lighting. This one is a tricky one, if you ask me, because it’s kind of arbitrary as to how exactly to get the intended results with analyzing the mesh’s distinct features.
- If all else fails, export the mesh by itself from Blender into UE4, use the UV auto-generator to create a UV lightmap in UE, and try that. If it’s practical and easier, cut the mesh into a few pieces prior to exporting. Then rebuild it in UE4, merge / group the mesh pieces into its whole, and then generate the UV lightmap for the final.