Can an external camera use a custom light source?

[SiliconPyro]

I've been thinking about how to make a sort of terrain radar that sees the ground in black and white, only showing topographic contour lines, or maybe contour lines over the terrain's mesh. My idea is to use a camera that can only see the light from four directional lights (coming from four directions) with cookies that would only allow light representing the elevation lines to get through. Hhopefully the result would be dark terrain with bright lines cast onto it.

I've never done anything more in Unity than some part making, so I'm not even sure this is possible.

[SiliconPyro]

Nevermind. The lines would be stretched on flatter terrain, which would not look right.

Back to the drawing board.