Shading breaking. Please advise?

[Bulwerk]

I am having an issue and wanted to pass it by the folks on this forum.

I have tried various ways to get around. Since this is a CAD import is contains a Normals tag and changing the Geometry in anyway completely ruins the phong shading so welding points and the like seem to be off limits. Anyone out there know whats up? Am I stuck with this problem?

Working with client provided CAD files for a visualization project and I keep running into odd shader behavior.
I am trying to simulate a metallic fleck paint with clear coat. Here is a picture of the problem.

Here is a wire frame of what the model looks like in the problem area.

Normals as they look in C4D viewport.

And some info passes showing what what the normals look like
Vertex Normal

Tanget normals

And just to make sure it was not just my material shader properties I used Silverwings very nice Car paint shader and the problem persists.

[Liketheriver]

Hy Bulwerk,

Is the material tag applied in uvw mode? this happens when the object don't have an UVmap and you apply bump or other uv-related stuff to the texture assigned to it

LTR

[Bulwerk]

Thanks for the reply Liketheriver

It does seem to be very UV map dependent. Here is a new render with better UV mapping but not perfect.

I guess my new challenge is trying to UV unwrap the super high poly model better There are so many co-planer surfaces with un-wleded points

[aoktar]

Some normals are reverted partially. Try to unify all normals.
Tangent or shading normals that the things is required to be checked, not vertex normals i suppose.

[Liketheriver]

glad to help Bulwerk,

for the uv unwrap you can try roadkill http://www.pullin-shapes.co.uk/page8.htm, is simply to use

LTR