I have just published a blog post on the Wessex Archaeology website entitled Interactive Landscape Relighting. It is about using Polynomial Texture Mapping (PTM) in a virtual environment, using LiDAR (airborne laser scanning) to create models of landscapes which can be illuminated by the viewer from any angle.
The post uses part of the Stonehenge World Heritage Site LiDAR data as an example, and you can have a go at changing the illumination on a section of the WHS yourself. I hope to make the file and a software tutorial available soon, so that you can download and view a larger version.
Read the full post over at Wessex Archaeology: Interactive Landscape Relighting (now with an actual working example!).