Now that I've finished my recent assignment here's anther link.
Terragen is a free photorealistic landscape rendering program that allows you to create images like these.
You can create image sequences of flyby's using a second free piece of software that's designed to work with Terragen. It's called Camera Path Editor.
Moreover, using a stereoscopic add on, this user created a 3D flyover of Mt St Helens.
When viewing, watch the video crosseyed so the pictures overlap, similar to those fractal 3D images that were so popular a few years ago.