I'm sure someone's already thought of this, but this just struck me. Another cool use for this technique... you can use your 2d export as a displacement map in your favorite rendering program.

Here's an example of my test depth map in plan view with camera set to parallel projection(very quickly modelled terracotta roof tiles

and the output when rendered on a single plane with it in the displacement slot and no diffuse:

and the output when rendered on a single plane with it in the displacement slot and a diffuse color map:

fun stuff!