lightmap issues after importing from blender

Not sure if I’m posting this in the right place but I’ve been on this problem for 5 days now spending lots of hours on it but going round in circles and it’s gotten really depressing. I’ve watched tons of videos on the problem/similar problems trying to find any kind of information that might solve it with no luck. When I import from blender to UE I get the typical lightmap overlapping error but I create the lightmaps in blender on a 2nd channel then import without ticking “generate UV’s” and they are still really messed up, yes the lightmap coordinate index is set to 1, the second channel. I’ve also tried using generate UV’s and different lightmap resolutions with no luck, they are better but still broken, the lightmaps look perfect in blender from what I can see although I could be wrong but once they are imported into UE the look different, sometimes with strange red lines instead of white. I have also tried pretty much every other option in the mesh editor, lighting and blender UV map and other settings but nothing seems to work and will love anyone who can help me now, i’ll post some screenshots

Are the UV’s showing up the way you created them in Blender?

Second image with the messed up walls are that the UV’s are overlapping massively. Third image the lightmap resolution is too low. The default setting is 64 pixels which is often too low, you can change the resolution for a mesh you can see there in the first screen under Static Mesh Settings.

The second is with the blender UV’s, which in blender look great but terrible in UE (sorry i didnt mean to send the 3rd and 4th as the same thing). The 3rd and 4th are when i auto generate the the UV’s but the resolution isn’t the problem, i’ve tried anything from 64 to 3000 and there’s still the same problem where the whole objects lighting properties changes. Here is how the UV’s look in blender

These are the same lightmap in the same channel but in UE and blender, in UE it seems they are overlapping a ton and no matter what I do they don’t repair, but in blender they look perfect to me. I don’t know why they change so much when imported into UE? I’ve tried changing all the import and export settings too with no luck

This overlapping issue is really strange, I think the problem comes from Blender and not UE4.

I dont use Blender but there are few problems that I can see on your last screenshot (from blender) of the UVs. You dont have any padding between the UV islands. If the UV islands are like that you have now, so when UE4 build lights most of the shadows will leak to the other islands and this will lead to problems like on your third screenshot from your original post. I can also notice that your uvs in blender are too stretched and not enough flat to produce good results in lightmaps.

I suggest you to go and do some tutorials on how to make uvs in Blender. I am sure that there is some automatic function like “Flatten” in 3Ds max, as it produces mostly good results on geometrical objects with flat surfaces. And keep in mind for padding between the UVs. :slight_smile:

Your UV’s in Blender aren’t done correctly. They are overlapping, you have verbs that are connected to other parts of the layout that should be separate. You see on the left side of your map around the center? Go back and mark all your seams again. Also remember your padding. Very essential when you are doing light mapping. Try to remark all your seams and lay it out again. :cool:

hello sorry I didn’t come back for a while and forgot about this post, been so busy trying to fix it and so frustrated it’s making me want to shoot myself in the head. I’ve watched videos and still have no clue how the UV’s should look ideally but I know i’ve tried all sorts of other UV settings and moving them around to different places and absolutely nothing works i don’t even know what to do anymore. I’ve watched a few videos on marking seams and UV mapping but unfortunately I have a low IQ and cannot figure out what on earth is going on

In UE4 on the left there it is showing many more polygons than are there on the right–are you combining meshes when importing to UE4? If you do that then that will cause your problems since you’ll have many objects overlapping.
If you have your lightmap UV’s set up in the second UV channel, make sure that when you import to UE4 that the option to automatically generate lightmap UV’s is turned off, otherwise it will take those UV’s to a new channel and try to flatten them and then assign that new channel to the lightmaps.

I even try to add a basic cube into blender, export and import to UE and bake the light for that and even that has problems.

this one is with a lightmap made in blender, it can’t even make a lightmap for a basic cube? and this one is with an auto generated lightmap in UE: it may not look so bad here but it’s much more pronounced when in my own scene. I have also tried to manually unwrap the cube which was very simple and add seams following a youtube video which what supposedly should have been a perfect unwrap, then adding a lightmap in blender or UE and having neither work with pretty much the same issues just in different parts of the cube

yeah i don’t use combine meshes, i have only tried that once, and i am definitely using the correct UV channel and not generating UV’s if using the blender one