Really weird shadows and lighting are appearing on a simple blender made Static Mesh, I have no idea why. I’ve been searching the forums for hours, and took all the steps I can to remove the shadows like –
Extra UV Channel for lightmap information.
Using Calculate Normals option while importing the mesh.
Unwrapping using lightmap pack option in Blender.
But still there are lot of weirdness going on as shown in the pictures below →
Before Building lighting:
you need a second uv channel on your object and lightmapCoordinateIndex should be 1, but you shouldn’t use lightmap pack in blender, because it does not create enough space between the UV islands. you need to unwrap and pack the UVs manually, with a few pixels between each island, and you need to split all hard corners (90 degree angles) into separate islands, or else you will get artifacts and bleeding. the big black L shape on your roof looks like you have overlapping UVs, which is bad for lightmaps,
Thanks for the reply Omnicypher! I Tried to unwrap UVs as you said, it would be great if you can inspect my blend file and tell if the light map is correct or not. And how can I make sure that my lightmapCoordinateIndex is one, Is that a setting in UE4 or blender? How can I set which UV Channel to Use for lightmap information? Also, Is blender the right program to UV unwrap things, or I should use some other program like 3ds max or C4D?? Here is the file.
if you have 3ds max, its automatic uv packing is better than blender, because it has padding, but you still should hand pack your UVs, so either software works just as well as the other, and blender’s unwrap is faster than 3ds max’s pelt unwrap, because you don’t have to relax by edges/faces/centers manually, it just does it automatically when you hit unwrap.
in UE4, right click on your object, and choose “Edit House_01” or whatever its called, and it will open the static mesh editor. in there, you can search for lightmapCoordinateIndex. lightmapCoordinateIndex IS the way you choose wich UV channel to use for light maps.
i looked at your blend file. your UV islands are way too small, and your geometry is very wasteful. your window frames and shutters have faces on the insides that no one will ever see, and they are wasting space on your UVs. you should delete those faces, and turn the corner edges of your window shutters into seams so it will unwrap nicely. after you unwrap 1 window, you can copy it around the house, then move their UVs to make sure each copy is not overlapping. if you don’t want to delete those inside faces for some reason, you should go through each face that will not be seen in game, and collect all of them, shrink them down and shove them into the corner, taking up less than a pixel. if they overlap it doesn’t matter, because no one will see them.
put this image in your UV editor. anything you want to have lighting information needs to be at least as large as a pixel on this grid, and padding between islands needs to be at least as wide as a pixel on this grid. this is for a lightmap resolution of 64:
