toon line having opacity instead of thinning ?

[adriyantandia]

Hi ! I've read some posts with similar issue and the solution/answer to that was due to the line being too thin, which arnold hence trying to reduce the opacity. For my issue here, I had different region maps on two different sphere (in the color mask), and added the facing ratio there to remove lines cluttering(espc on a more complicated asset)

the problem is as you can see here, the 'outer side' of the lines, where it is overlapping each other (which i assume the contour works with half the pixel inside the alpha of object, and the other half outside the alpha ) are facing out, feels like having a transparency even though i just plug it in through the width.

is there any way to fix this issue ? thanks ! 🙂