LightMass artefacts

[Rodion]

Hello, I'm creating car model in TrueSpace, using mirror mode, and overlap UVs for left and right sides. I export from TrueSpace in COLLADA and then use Autodesk FBX converter. Then I import model in UDK, taking normals from model, because there is no smooth groups in model and autocalculation creates corny specular highlights. Then I autogenerate second UV set for LightMass ( it has index 1, 0 - is UV set from TrueSpace ) and choose UV set with index 1 for lightmass. And Light Mass gives corny results, similar to sharp corners in specular highlight with normals autogeneration. You can see screen with lightmass artefacts in this 7zipped archive - "http://letitbit.net/download/67110.62bb276c18be772007810fcc113f/KITT_Car.7z.html".
Also - I've put model with 1 UV set in archive in COLLADA and FBX text formats. So the first question - Why there are such artefacts - do LightMass calculation uses Smooth Groups or there is other reason?
Also, I've put in archive model with 2 UV sets exported from TrueSpace - also in COLLADA and FBX formats. It seems that FBX converter recognizes second UV set and put it in FBX, but - when I import model with 2 UV sets in UDK -there is only 1 UV set and it is second UV set from model. So - how can I solve this problem and import both UV sets, if there will be need in custom UV set for LightMass?

[F4ll_ouT]

Oh nice I have to seek the downloadbutton and loose a ******* minute of my life for ads and all that just to watch a screenshot although I won't probably be able to help you.
The ad even looks like a cheap wow clone. Oh I dont' even have 7zip installed. That's a nice car. Looks like it's going to be KITT ;D

Ok sry for offtopic I was just kidding. The problem is very simple I think.

and overlap UVs for left and right sides

Do NEVER EVER overlap UVs for left an right sides. I also liked to do that but I got many problems with it.
Try to unwrap your mesh without overlapping and you should be just fine

[Rodion]

UVs overlap only for diffuse texture; for LightMass calculation theoretically the other non overlapping UV set is used, that is generated by UDK itself. So why do LightMass calculation depends on overlapping diffuse UV set? I think that the problem is in lack of smoothing groups - they might somehow be used in LightMass calculation.
Making non overlapping diffuse UV set for car will require 2 times bigger texture or decrease resolution 2 times; or there is really no other way and even diffuse UV set must be nonoverlapping?
Sorry for that file hosting.

[Rodion]

I understand now where the problem is - without smoothing groups UDK calculates tangents and bitangents not right, and because of that Global Specular illumination from light mass looks edgy. Bump mapping also is edgy, so the problem is really in lack of smoothing groups, and now there is need to create custom tangents and bitangents generation for COLLADA and hope that FBX converter will recognize them and UDK then recognize them in FBX; or somehow create smoothing groups.

And another one question - when importing .x files in DirectX 9 there is ability to autogenerate tangents and bitangents and there is ability to set the angle between triangles, below which there is sharp edge between triangles and higher of which there is smooth transition - so is there such ability in UDK - to set somehow this angle in model import for normals, tangents and bitangents generation?