Don't know about a complete guide, but you can use a photo to create a terrain by adding a photo via the terrain editor. There's a tab for this in the box on the right of the TE screen.

In the TE, look for the Editing Tools box. The last tab is 'pictures'. Click on the 'LOAD' option above one of the little square images. This will open a browse box. Select your image and away you go!

Hope this helps.

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All the Woes of a World by Jonathan Icknield aka The Bryster

And in my final hours - I would cling rather to the tattooed hand of kindness - than the unblemished hand of hate...