I saw some kind of example done in Vue a couple of years ago of an old English countryside. The person used color air photos and created bump maps- imported those in Vue's terrain editor to make them 3D, -and then re-mapped the photos on top. The idea was to locate ancient forts and battle sites. The 3D effect helped to indentify ancient roads, which in turn helped show where the ancient camps were. Unfortunately- that's all I know and can remember about it.