Shading Normals are not respected?

[willMarciano]

Hi, 

Is there a reason Arnold seemingly processes normals incorrectly in its lighting calculation? I've recreated the scene in Redshift (same normal maps, same everything) and it looks as expected. 

Arnold clearly understands the Normal information as shown by the N AOV/aiUtility shader in ndoteye mode. Is this the result of some under-the-hood AO calculation? More pressingly, is there a way around it?

 

For clarities sake, I've tried:

• Enabling subdivision/tessellation,
• Checking "Ignore Normal Smoothing" in render settings,
• Switching to aiStandardSurfaces (from aiToons)

I am using tangent-space normal maps, piped through a aiNormalMap, into the 'Normal Camera' attribute. 

Thanks,

Will