Normal Map Seam Issue

Patackular

Hello all,

I feel like I have a reasonable grasp of normal mapping and I have a feeling this might be a really obvious mistake, but this has really got my mind in a twist. I have tried projecting normal maps in both xNormal and 3D Studio Max and yet I still have a seam running down the back, base of my traffic cone model, as well as around the parts of the hands.



I have a feeling that this could be down to the cylindrical shape of the model, causing issue with the light being calculated to create a smooth transition between each side. Perhaps instead it is because the unwrap is not laid out so each side is straight and at the same angle. If that is true and each side needs to be unwrapped vertically, then surely the unwrap will be uneven and distorted, given the cone shape of the model.

Can anyone confirm this?





What I also do not understand is that even using a uniform blue normal map creates the error.

Kurt Russell Fan Club

That probably means your shader is broken. Which shader are you using? Or if you're using the max scanline renderer, grab a viewport shader.

Different shaders use different maths for interpreting your normals. As a general rule, though, if you apply a flat 128,128,255 texture as a normal map and the mesh looks any different to how it looks without normal mapping, your shader/rendering is broken.

Patackular

Thanks, Kurt! It was the default one in Max. That is soo frustrating. Seems to be the case thought. I cannot even seem to get Xoliulshader working.


Can you recommend any other shader?

Hang10

3Point has a really nice viewport shader too. They have a paid version as well as a free lite version.

Kurt Russell Fan Club

You'll also have to switch from nitrous to directx for your viewport. Go to (I think) tools-preferences-viewport then click the button at the bottom (change driver?) and pick direct3d.

Yeah 3 point is good, xoliul is good (my default )

Numerator

The vertex normals and tangent vectors have to be the same at the seam.

Patackular

@Hang10
Thanks for the suggestion. Got it setup and it looks like a really nice shader.

@Kurt Russell Fan Club
Thanks for that. Xoliul’s working now.

@Numerator
I think you’re right. I have tried the file in Max 2011 on my laptop and I have the same error and despite getting the shaders working, it looks like it is definitely the normal map causing the issue. Or rather the UV layout.



Is it the same as this issue?

Mask_Salesman

Make sure "invert green channel" isn't ticked? Most shaders have that option.

Patackular

Thanks Mask_Salesman, but I have flipped the green channel back and forth in the shaders and in Photoshop.

yodude87

im having the same issue in an asset im working on currently. ill post some pics later when i get back home. if soeone finds a fix for this it will be greatly appreciated :P

edit: http://forums.epicgames.com/threads/890986-Solution-UDK-Map-Seams-where-UV-seams-are

Patackular

I really thought re-unwrapping the base so each side were laid out at the same angle would solve this.



But no luck

Pabs

is it possible for you to share the file and normal map for me to try?

Ghostscape

3ds Max might be gamma correcting your normal map (it loves to do this and it is shitty as hell).

Apply your material to a plane or cube, duplicate the plane or cube, and rotate the duplicate 180 degrees. If the flat parts are lighting differently then they're being gamma corrected.

You can turn off Gamma Correction in the options somewhere, then re-create your shader.

Patackular

@Scapulator
Much appreciated! I was just about to share the files with you when I read Ghostscape’s reply.

@Ghostscape
Why does Max do this!? Thank you! I have unchecked ‘Gamma Correction’ and it seems to have removed the nasty seams



For anyone else with this problem, I am running Max 2013 and it is under:
Customize > Preferences > Gamma and LUT > Enable Gamma/LUT Correction

It looks as if unchecking Gamma Correction takes a lot of light from the scene, despite my lights being turned up to around 1. I am sure I can adjust these to light suitably though.

Thank you for everyone's help with this!

Pat