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Normal map behaviour

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Hello,

 

I'm working on a symmetrical low-poly model and would like to make details pop up with a tangent normal map.

 

So I drew some stylised patch of hair and the nose in Photoshop and generated a normal map with Crazy Bump.

 

What I see is details from the normal map reacting differently from one side to the other.

 

Here is a 360° render + the normal map (yeah I know this is a weird guinea pig lol).

 

The stylised patch of hairs looks fine at 15°, we don't see much at 90° and there's nothing at 130°.

Then, when we switch to the other side, it looks fine at 220° and 270°, but we don't see much at 345°.

 

I searched a bit about that on the internet but all I found was articles about how a tangent normal map render better than a world space normal map.

Is it a limitation from normal mapping or is there some ways to have a consistent shading from any angle ?

Thanks in advance.

Guinea Pig Punk 002_NRM.png

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I think it's a combination of normal maps just working this way and your shader. If you'd reduce the roughness of your model you'd see the crevices way, way better. When the viewing angle is very straight there's just not much contrast in there to make it pop, which is why it looks like the detail is vanishing.

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  • 4 hours ago, DasFrodo said:

    I think it's a combination of normal maps just working this way and your shader. If you'd reduce the roughness of your model you'd see the crevices way, way better. When the viewing angle is very straight there's just not much contrast in there to make it pop, which is why it looks like the detail is vanishing.

     

    Thanks for the reply!

    Can you explain what you mean by roughness ? My shader only has a straight color, an art shader luminance (at 50%) and the normal map (at 50% or something - didn't pushed it too much since it's causing very dark shadows on the mouth). There's also some reflectance.

     

    Edit :

     

    Also concerning the viewing angle, I'm not surprised that it looks a bit flat from a frontal view, but it seems that details are more visible from the left than the right.

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    I guess I don't really see the problem either.  I think this is how normal maps should look, and now that I hear more about your material settings, particularly that you're using Luminance, I'm not at all surprised by your result.  My understanding is that normal maps react to lights in order to fake shadows.  If your material is basically a light source, it's going to drown out any shadows, especially when the polys are generally facing you.  If you need it to be luminant, you will probably have to use your PS texture as a fake Ambient Occlusion and pipe that into the luminance to drop it down in those wrinkled areas.

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  • Thanks a lot @natevplas! I totally forgot about using occlusion. I tweaked the shader a little and I really like the results :)

     

    Here's an update :

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