weird normal map issue

Joao Sapiro · Jun 2007

I painted the normal in bodypaint to get rid of the seam, ( i cant view just the R,G.B channels in the aplication thou ) and there is no seam in the texture, but the normal map still displays weird .

I checked the normals of those faces and nothing seems wrong to me

Mongrelman · Jun 2007

Hmm, border between smoothing groups maybe?

Joao Sapiro · Jun 2007

there are no overlapping vertex nor extra edges :S this is becoming weird ehehe...

MoP · Jun 2007

It's a UV split, which always causes issues in normal maps.
What app are you viewing it in, and have you tried any custom shaders (or if you're already using a custom shader, try a different one).

Sometimes a better shader can help hide this issue.

Joao Sapiro · Jun 2007

im viewing it in 3ds max viewport , but the render using F9 has the same issue

MoP · Jun 2007

Yeah, but what I mean is, don't use the standard out-of-the-box "DX display of material" (or even worse, the old Metal Bump shader thing).
Try using a DirectX Shader material using something like JIStyle's skin shader, or Ben Cloward's HLSL normal map shaders, they hide seams better than standard Max shaders.

Joao Sapiro · Jun 2007

yeah the thing is this is for a job , and they want me to clean the seam , the normal wich is causing it is cleaned

EDIT : and i cant use any shader besides the normal max one

Jesse Moody · Jun 2007

hmmm have you checked your blue channel? I know that seems off base but when I was cleaning something up a while back somehow my blue channel got jacked and it made seams like this. It was weird.

Just a shot in the dark.

Rob Galanakis · Jun 2007

[ QUOTE ]
yeah the thing is this is for a job , and they want me to clean the seam , the normal wich is causing it is cleaned

EDIT : and i cant use any shader besides the normal max one

[/ QUOTE ]
That's like saying you need a sphere but they only want 2 faces...
Try it with Ben's shader, if it works, explain to them its the shader and not the asset causing the problem and there's nothing more you can do from your end (by showing them screenshots with the different shaders).

Joao Sapiro · Jun 2007

yeah i explained it to them and they were like meh ok, just clean the seams in the maps. I tried the best to clean it , but as someone mentioned , it depends on the shader.

thank you all for the help !

StJoris · Jun 2007

HMm well with a strong angle change depending on the high-poly, there could be a seam in the normal map, but that results in not showing a seam in the render, if that makes sense. Can you try rebaking the normal map, but this time don't clean out the seams, and see how it shows.
You say you paint them in mudbox, that means you use the highest sub-d and the lowest and bake it?

I'm not really a guru on this subject though, so I could entirely miss the makr.

Mister Sentient · Jun 2007

Have you tried inverting the green channel of the normal map? Some shaders are weird like that. Ultimately it depends on the engine which will be displaying the normal map. Maybe your employer could give you an example of a normal map which works in their engine.

MoP · Jun 2007

I think the problem might be that painting over a seam in a normal map like this isn't exactly the same as painting over, say, a diffuse seam.
I might be wrong (this is probably a better question for Per128's big thread on normal mapping), but when UVs split the lowpoly tangents are changed somehow, when relating to normal maps anyway. So painting over a seam to make the normal map colours match up, isn't the same thing as actually hiding the seam.

I think StJoris might be more accurate when he says it's a better idea to re-render the normal maps and see how they look.

Noren · Jun 2007

In order to be able to paint over them, the seams have to be parallel. Or you paint over it using 127,127,255 which of course removes also the benefits of your normalmap in that area. If you have rotatet uv-chunks try to render with different SG's set for differently rotated chunks. (Not neccessary for max's renderer ). The Normalmap WILL have a visible seam if seen as RGB/diffuse on the model. If Engine and Renderer match up, the final outcome should look ok however.

kite · Jun 2007

got any pics of the normal area on the texture sheet? you could dupe the low mesh and reuvw the problem area, then render all your texture work from the problem low to the cleaned low as self-illuminated diffuse maps.

Joao Sapiro · Jun 2007

wow you guys rock ! i was able to do some tricks with the edit normals, and with all maps cleaned, the seam is still there, but i guess their engine must take care of it. Ill post some examples later.

P.S - mop, check ur pm :P

Noren · Jun 2007

[ QUOTE ]
you could dupe the low mesh and reuvw the problem area, then render all your texture work from the problem low to the cleaned low as self-illuminated diffuse maps.

[/ QUOTE ]

While that might work by pure chance, normals have to be recast in all cases where the orientation of the uv's change between the two uv-sets. A normalmap is no diffuse map, so you can't treat it like one.

kite · Jun 2007

yeah good point. I should have tried that out for more than stitching horizontal seams

Noren · Jun 2007

Well, since you are using two versions of your model anyway, you simply have to add the normalmap to the output-section of the rtt-window and you are on the safe side.

Just for rendering a diffusemap from one uv-channel to the other you don't even need projection or a duplicate of your model.

weird normal map issue

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