The contour filter outlines my UV islands. This artifact is minimized by changing setting in the aiToon>Edge Detection>Normal Type to geometric normal. Although this does work differently for every geometry piece, in general diminishes the effect of this artifact, but it is still there.
I tried multiple combination of settings and adding a normal map in the Geometry section in the shader. Nothing works this far.
Thanks in advance!
Working on Maya 2019.3
Big geo with 20 UDIMs, multiple pieces, 4K displacement map (tangent).
Work under NDA. Sorry if I can't show the geo or share the file in any way.