How to get the surface height at a point in Lua

[unicorndog]

Is there a function that returns the height of the surface (land,building, whatever) for a given point?  land.getHeight gets the elevation of the surface, but if there is a building or other object on top of the ground, it does not take that into account.

Currently the only way I can figure out how to do it is to have a hidden probe ground object that I spawn on the coordinates (at elevation zero), this spawns it on top of whatever surface is at the coordinate and then I get the height and then remove.