Weird Shadows When importing FBX

Hi everyone. I’m new to Unreal Engine and since my plan is to start using it only for shading and lighting, i’ve been practicing importing and exporting FBX these last few days. However, i’ve come across a problem that I cannot seem to understand. Whenever I import certain models, complex models usually, I cannot build the light unless there is an unreal engine object in the scene. I mean, if there isn’t an object from the unreal primitives library, then the light refuses to build, it freezes at 85% most of the time, and no matter how much time I leave it, it does not finish. On the other hand, when I do add an object from the unreal library, the light does build, but I get really weird shadows, no matter how much I crank up the lightmaps resolution. I’m pretty sure it has something to do with my lightmap UV’s, but I can’t figure out what the problem is. I’ll leave both a picture of my 3 sets of lightmap UV’s, for the three objects that I imported, and the strange shadows that I get. If anyone can figure out what the problem is, it would be lots of help.

Thanks and sorry for any bad english.


The problem about your lighting not finish building seems to be the same as this problem I had myself: Very long (maybe infinite) lighting build times on empty or very small scenes

It’s basically a bug with very small scenes. So that’s why it works when you add a primitive from the engine. That primitive is probably bigger than your object, or the combination of that primitive and your object makes the scene big enough. So, unless you want to create a scene with only a small object, it shouldn’t be a problem.

About your lightmaps, I’m not sure. Your UVs seem ok. Make sure you created them in the second channel and that the model is actually reading the lightmaps uvs from channel 1. You can see and change that in the property Lightmap Coordinate Index in the static mesh editor. Also, when working with BSPs, you actually have to lower the resolution to increase the detail.

I hope this helps to find your issue. Greetings!

Thanks PacoChan. It seems that it was a bug from the 4.9.2 version. Switched to 4.8.3 and light builds Ok. However, I’m still getting those weird projected shadows, in both BSPs and imported planes. I only get them with THAT particular model. If it isn’t lightmaps then I don’t know.