Draping images over surfaces in Civil 3D

Having recently overcome various difficulties to successfully drape an image over a surface in Civil 3D, it may be useful to pass on a few points I have learned. There are various posts and videos out there that helpfully go through this process, but some of them (including Autodesk sources) contain information that is irrelevant or just plain wrong, and none of them contained all  of the information I needed to complete the task. I used Civil 3D 2015 for this, but the principles apply to all recent releases. Here is the basic sequence required: In the drawing containing the …