Many thanks to Matt Fairclough of Terragen for permission to use his image. 
His website with an image and movie gallery is worth visiting : http://www.planetside.co.uk/terragen.

Some others with some excellent images on their website:

• Richard Horne on his 3dem website:   http://www.visualizationsoftware.com/3dem.html
• Golden Software's surfer program:     http://www.goldensoftware.com/products/surfer/surfer.shtml
                                                                       

    From : http://www.goldensoftware.com/gallery/gallery-9.shtml (with permission from Terradat Geophysics)

David Douglas, one of the Canadian pioneers of Digital Cartography in the 1960s, now retired,  is a Visiting Professor at the University of Gävle in Sweden.  His website includes computer generated images of terrain produced by himself and his students at:  http://www.hig.se/~dds/research/vublok/renderit.htm