Sinemap Matching?

Hey all,
I need some math ideas here.

I need to match a PP material to the sine interval of a mesh that is moving via tessellation offset.

Is there any way to detect a visual collision or something similar that would enable me to define / find / analyze the high/low + timing of the sine?

the only way I can think of currently is to film it and analize for the time, but the sine interval (or the distance between high/low) is not exact enough to maintain the same rhythm…

just so it’s clear (which it’s probably not, I’ll need to add a picture/video).
The PP looks at the camera, and decides if to Add/Subtract the custom stencil of the mesh from from the mask created “below z location”(same oscillating z value) based on the camera position being above/below the moving plane.