Toon material creates undesired lines


I am having difficulty with toon material. There is a big rectangular light just at the front of the section. If I apply toon material to whats behind it ie walls a big line across the entire light appears.

Any ideas why ?

Thank you !

Maybe you can use an emitter instead and set invisible for the camera. Are the light and the clipping plane at the same place? Maybe it’s an intersection artefact and it helps to move the light.

I think that was the problem. Clipping plane was aligned with the light itself. Thanx for the interest !