This is how to make 3D terrain maps "by hand", or with a lot of manual labor. Not how to use Mapbox or Cesium-JS to make an interactive map. "It is very costly to change, say, the direction of view, in the final stages of map production. Changing the direction of view by even one degree would mean starting over from scratch."

I've been trying to do 3D terrain maps in Mapbox, and real elevation isn't working yet. They only have "hill shading", which is what graphics people call bump mapping. They have an experimental project to use Three.js with Mapbox, which looks very nice, but it's just a demo right now. Cesium-JS supposedly can do 3D elevation maps, but I haven't tried it yet. These all produce live "slippy maps", like Google Earth - you can pan, zoom, rotate, and change the viewpoint.