I opened the file in Photoshop and turned it into gray scale.
I then bumped up the contrast a little until it looked like this.
Then I put a new layer on the rock photo and drew masks and then used a big blurry brush to create the edges of the rock. As I worked I kept in mind that black would do nothing and white would be raised up when a applied the bitmap to a relief,
Then it was time to build a relief in EnRoute. I first created a flat relief.
Then I imported the rock bitmap, selected the relief and the bitmap, opened the apply bitmap command and typed in a value of 0.25". The result was very grainy and not at all what I wanted.
The solution was simple. I took the bitmap back into PhotoShop and added a blur. This would get rid of the graininess. Then I applied it to the flat relief once more. The results were much more to my liking.
Then I imported the bitmap I had created using the large fuzzy brushes. I applied this as a second layer.
This created the sharp layered edges in the rock similar to the photograph I had first been given. By creating and applying more layers I could have achieved a much more dramatic effect with more subtleties.