I’m new to the engine, which is quite exciting. But while I’ve been throught the docs and tried a few things on my own, I keep being stuck on a problem. I’m using 2013 to export my static meshes. The FBX exporter is set up as the doc says so. But, once my asset is in the Unreal scene, and after I’ve build the lighting, my mesh appears covered with lots of little gray, black and white squared shapes. Apparently, the lightmap is showing on top of the textures… So I’ve tried to export my meshes with a dual UV channel, and this time it works.
But the process is tedious, I got some trouble keeping the UVs right and as far as I can go throught the docs and tutorials, I’ve never seen anywhere this “dual UV channel” thing. Is this the right process, or am I completely wrong ?
So, could you guys give me a few pointers, please ? Any help would be appreciated.
Yes, the second UV channel is for the lightmaps. It has a few requirements, all the UV’s need to be in the 1x1 space and can’t be overlapping or inverted.
For best results, there needs to be enough space between UV islands so that it has enough room to create extra pixels for bleeding, otherwise you can get errors around the edges of the lightmaps.
This should help with getting 2nd UV channel: ?v=BY-nKxyHKRc
You basically need UVs in second channel not to overlap and use as much space as possible. Also remember to change Lightmap Resolution from 32 to something higher to get better quality of bakes. Especially on bigger, more important objects.
This is also great resource: https://docs.unrealengine/latest/INT/Engine/Content/Types/StaticMeshes/LightmapUnwrapping/index.html
2nd UVs are fairly common with engines that use static lights. The reason being that there is zero performance hit for shadow rendering during run-time. You can get great shadows with a good lightmap resolution and good lightmap UV layout without having to to worry about shadow calculation.
The link that provided above for World of Level Design is a great start for understanding lightmapping and how to get great results.
