Pre-made height map for a planet

Hi All!

I'm working on making a detailed planet in Unity. There is a lot of material and tutorials on how to make procedurally generated planets in Unity. However, I don't want to procedurally generate any terrain. I already have a custom made heightmap and skin for the planets terrain itself. So that leaves me with the question that if there isn't anything out there on how to do this, is it possible to map a planet with terrain that has already been generated?

 

Some more details may be required. Unity terrains are flat but with code they could be converted to a series of convex meshes that could join up to make a sphere. You would need to work out the best way to subdivide the sphere for the meshes.
If your sphere is made up of near squares and you can tolerate some distortion, it makes it less complex because you can work directly from the square terrains and textures. if your sphere is more like a soccer ball of hexagons or a geodesic sphere divided into triangles, it becomes more complex. The image below is for reference.

 

Octohedron dual hemisphere




see animation
https://i.stack.imgur.com/PCB0U.gif