Need help with mirrored normals for UDK

Helixos

Sorry for posting about this twice (as I've just posted about it on my WIP thread) but here it goes.



As you can see I'm having an issue with normal mapping my symmetrical T-Rex. Feels like I've tried everything and nothing is working. Can't seem to understand EXACTLY what the problem is.

Really would appreciate it if anyone could help me. Thanks!

jsargent

you might get more help with this in the technical section of the forum.

Helixos

jsargent wrote: »

you might get more help with this in the technical section of the forum.

Ugh. Silly mistake. It's been a long day! Thanks man.

Clark Coots

check your face normals?

_DeadPixel_

I read something a while back about this problem with UDK.
The guy's solution was to open the texture in photoshop, select the green channel and deselect all the others, then invert the green channel and turn all the channels back on then save it out.
I'm not sure if it'll work in your case but it's worth a shot.

Helixos

coots7 wrote: »

check your face normals?

Sure did. All the normals are fine, facing in the direction they should be.

_DeadPixel_ wrote: »

I read something a while back about this problem with UDK.
The guy's solution was to open the texture in photoshop, select the green channel and deselect all the others, then invert the green channel and turn all the channels back on then save it out.
I'm not sure if it'll work in your case but it's worth a shot.

Just been looking at your stuff, loving the Deadlander dude!

All flipping the green channel does is throw the problem on the other side of the mesh, i.e. the convex side becomes the concave and vice versa.

Have you never come across this problem then?

Selaznog

Yah my original guess would have been face normals. I recently discovered that if you mirror stuff in engine things will be weird. Which bugs me, because I'm pretty sure most everything is mirrored in games...there has to be a way around it.

Helixos

Selaznog wrote: »

Yah my original guess would have been face normals. I recently discovered that if you mirror stuff in engine things will be weird. Which bugs me, because I'm pretty sure most everything is mirrored in games...there has to be a way around it.

I wish it was the normals It's got to be something to do with the fact that the UV islands are obviously mirrored, and therefore are producing 'mirrored' results esentially. The way I'm seeing it is if I find a way to 'evert' the mirrored UV islands without flipping their positions in the unwrap then this should fix it.

Can't afford to waste another days work trying to figure this out... Thanks for the reply though :thumbup:

_DeadPixel_

Thanks mate. Nah, I've never had this problem before.
UDK can be an utter tart with mirrored uvs but I'd say it's likely something to do with your face normals - it's the only thing I can think of that would affect the normal maps direction.
I spent a while travelling the inter-web for you and still can't find any answers to the specific problem.
If I were in your situation I'd step back to the mesh flipping stage and go from there, just to make sure I didn't miss something.
Best of luck!

Helixos

_DeadPixel_ wrote: »

Thanks mate. Nah, I've never had this problem before.
UDK can be an utter tart with mirrored uvs but I'd say it's likely something to do with your face normals - it's the only thing I can think of that would affect the normal maps direction.
I spent a while travelling the inter-web for you and still can't find any answers to the specific problem.
If I were in your situation I'd step back to the mesh flipping stage and go from there, just to make sure I didn't miss something.
Best of luck!

Y'no, you're all probably right with the face normals thing and I'm just being super dumb here. Guess I'll just take your advice and go back to the mirroring of the mesh. Cheers for having a look for me though, really appreciate it!

Arac

Have you tried moving the mirrored uv islands back into 0-1 space?

There's no reason why they can't overlap unless when you're actually baking your normal maps.

PogoP

Also I know it sounds silly, but try resetting your models x-forms before exporting! Seems to fix every problem I have recently, heh.

Helixos

ARGH! Nothing wrong with my mesh in the end, simply had to have both "Import Tangents" and "Explicit Normals" unchecked on import.

Well there's 8-10 hours I won't be getting back. Least it's fixed though!

Cheers for your contributions Arac and PogoP!

Der Hollander

Not exactly relevant to your problem per se, but now that you've got it in engine with the normals facing proper, a second UV set with unique UVs for a detail normal map will help hide the symmetry in the final product.

Rekmar

explicit normals only ever make a difference for static meshes, as it's a feature not implemented in skeletal mesh importing
setting my normalmap compression to NormalMapUncompressed usually does the trick for me

SanjiWhite

Maybe this helps: http://www.polycount.com/forum/showthread.php?t=116922