What's working: I have a solution for loading in topography using terrain tiles. Each tile occupies a plane as mesh. The image on the plane can then be any map tile source. Each plane mesh is a child of an object3d and offset accordingly to create the overall terrain.
The Question: I am not sure the best way to go about having an irregular shape inherit 3d surfaces. This shape could be drawn or imported as KML. Is there a way to use a vertex shader to inherit the topography? I would like the topography as a mesh so that I can interrogate the topography of the shape. In this way it is different from using a shader to paint the surface as a mesh result is needed.
I do not yet have code for this to share as I do not know where to start. Vertex shader? Constructive solid Geometry?