UDK Shading issue

InProgress

Hey folks,

I'm currently working on a scene inspired by Snefer's work with as few textures as possible. When I bring meshes in UDK, I get shading issues. The issues appear even after building the lighting. I'm exporting from Maya with FBX Exporter 2013.3.



First UV channel.

I tried offsetting the UVs by 1, but there was no change.

Things that I tried but didn't have any effect:
- Making it one smoothing group
- Importing the mesh without tangents and binormals.
- Changing the compression on the normal map in UDK.

I found a fix for this by making having less islands overlapping, but I keep encountering the issue on other meshes, even when the UVs aren't overlapping.

Any help would be appreciated.

r4ptur3

Is the artifact baked into the normal or diffuse maps? If not, try turning off "import tangents" when you import the mesh. I know epic says otherwise, but it ruins mirrored normals.

BNielsen

You should also make a separate UV map for your lightmaps(and select it in the statis mesh settings by double clicking on the mesh settings in importer), but if they're showing before you bake the lighting, it could be the tangents mentioned above.

I used to run into a lot of problems with mirrored UV's. I don't anymore, for some reason... I'll have to take a look at one of my old files and find out what I used to do differently.

InProgress

@BNielsen: I do have a lightmap properly set up.

Turns out it wasn't the import tangents the problem. Turning off tangents on import did improve it slightly, but I guess the problem lies somewhere else.

I've uploaded a mesh that with the problem.
https://dl.dropboxusercontent.com/u/565299/UDKShadingIssue.zip

r4ptur3

is this the correct mesh? looks like you gave us a window.

InProgress

Sorry, I should have been more clear. That's another mesh that has the same problem.
I managed to fix the L piece by making the UV maps cover the entire length. So instead of 2 islands the go perpendicular, I have one longer one that bends in the middle.

r4ptur3

Here's what the mesh looks like when I imported from maya. There's no diffuse or normal map on the mesh but everything looks as expected. I do not see any visible artifacts other than the hard edges on the interior of the window (which were also present in the OBJ). Are you exporting from max or maya? Are you positive the errors are not present in the maps? Are all polys UV'd in the other mesh? I'd check to make sure the meshes match in your modeling package and in UDK.

InProgress

Thanks a lot for the help. I managed to fix it. The problem I kept having was because I had separate islands facing different directions. This caused issues with how UDK was displaying the normal map on the meshes. Thanks again.