I do not have relevant experience in this field, but a Google Search for '2d to 3d photo' brings up some good looking links like this: http://www.download32.com/t3d---2d-to-3d-converter-d19457.html

I think some adequate blurring might be needed to get good base material for  a height map.

But for now my Googling is as good as yours. Good luck!