A group of students at the Media and Machines lab of Washington University in St. Louis has developed Live3D, an Google Earth-powered web application that allows users to transform photos into 3D geometry in Google Earth. If you give the application a webcam URL, then the geometry of the scene changes as the webcam image refreshes. So, you can recreate the Eiffel tower in 3D and get a live, constantly refreshing 3D model, instead of the static Sketchup model.
Once a user has built up a scene enough, the camera is automatically calibrated, revealing its location and orientation (for example, in this scene, the position and orientation of the camera is automatically generated, which closely matches the real webcam image).
Live3D is a web-based application that allows users to update the geometry and textures in Google Earth to see what the world looks like at this very moment. Users are encouraged to take one of the many outdoor webcam images and embed them three-dimensional space, constructing a scene with up-to-date images.
Live3D can also calibrate camera images and infer the camera's location and orientation. So, without leaving your desk, you can geo-locate and geo-orient a camera (usually to within a couple meters).