Help me out with UV Basics -- Program Specific vs 3rd Party?

Development Rendering
1

I know this is a rookie question, but after much searching I haven’t been able to understand yet.

should UV maps generally be created in the program models came from, or is there a third party / ‘easy’ solution for creating needed file to render models correctly?

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I’m often having the issue where a model turns black when lighting rebuilt, and am trying to follow threads and tutorials but could use a quick tip here from someone who got past this hurdle.

Thanks

2

Typically you’d create the UV’s for your mesh in your main 3D software before you export to UE4 and it will contain them when you import to UE4. For lightmap UV’s you can get better results by doing the UV’s yourself, there’s some automatic methods but they don’t do as good of a job since they usually put the UV seams in bad places or they split things up too much. UE4 has an option to automatically generate lightmap UV’s (and it’s on by default so you need to disable it if you have your lightmap UV’s created already) but all it does is it just copies the existing UV’s to a new UV channel and runs an algorithm to flatten what’s there, if the seams aren’t in the right places already then it won’t be able to do a good result.

3

Hi!

Most people would say to create your own lightmap in your 3d software but I’ve heard big names creating them inside Unreal…
I always make them myself in 3ds max (or 3dcoat)…
If your mesh is nicely uv-d for texturing then you can get nice results (lightmap uv) inside Unreal. You just have to set from which uv channel you want Unreal to create it (material uv channel) and where to (uv lightmap channel).

Black objects/polygons after building light is usually uv map problem or flipped normals…

4

Thanks for responses both of you!

Sorry to seek clarity here, but I’m still a bit lost.

I have some .OBJs (body and legs of lion) coming from Cinema 4D, and some .OBJ (converted from .stl) exported from Fusion 360.

I understand Cinema 4D has some kind of ‘auto generate’ UV function, but don’t think Fusion has it.

How would you guys go about creating UVs for high poly / triangle stl / objs? (I know Maya can import stl).

Thanks for tips.

5

The .obj format can only contain one UV channel, so what you’d need to do is bring the meshes into C4D and set up your UV’s there, first UV channel is for your textures, it can be overlapping or bigger than the 0-1 UV space, the second channel is for your lightmap UV’s, it can’t be overlapping and must be within the 0-1 UV space. Export to FBX format and import into UE4, make sure to uncheck the option Automatically Generate Lightmap UV’s in the Import window (like I said, this option isn’t a complete automatic solution and it’ll mess up your settings if you already have lightmap UV’s)

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hey darthviper107,
thanks for the more full explanation. LOL I’m still a bit confused, so I guess I’d better go back to the manual, using your advice as a starting point.

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Very important point: the UVW-Tags in Cinema 4D are named UVW by default, but both need to have a unique name so i’d recomend using something like UV0, UV1 or UV_texture, UV_Lightmap.
Also when you use a second UV, make sure that your material Tags are on the left side of the stack.
I’d also recomend using .fbx export preferably the fbx 2010 v6.1, since some Versions of C4D have an issue with the newer fbx versions.