Syncronize Web Cam with Real Desktop

Syncronizing your webcam to your desktop would be the ultimate feature for bumptop. Basically, if you have a webcam, you would position it to view the desired spot on your desktop in the real world. After which, the user would probably have to specify angles and edges as well as surfaces and objects. The desktop background would be what the camera sees, and your icons would interact with the onscreen image of your desktop.

If possible, you could take this to the next step by constantly logging the cameras position by seeing which direction the pixels are moving. This in response: When the camera is moved to the left, the icons would slide to the right, as to appear they are physically planted on the desktop.

While moving the camera, other icons would come into view that you had origionally placed out of view before. So basically its like a real desktop, just the only way you can see your icons is if the camera is looking at the position on your desk where the icons digitally are.

Inorder to accomplish the digital physics, icon angleing, etc, you can do this several ways. But keep in mind the main goal is to keep this as user friendly as possible. Heres 2 ways i have thought of that would be the easiest to program:
1) Make the user draw lines on the image of the real desktop, tracing the physical faces of the real desk. The angles would include the Borders of the desk, the front face, the desk surface(that icons would be on), the borders of the camera's view, and current camera position. This will tell what the icons are on, where they are, when they are about to fall off the desk, and where the are on the screen.
2)(harder) Allow the user to make a 3D model of the desk and position a representation of a camera so the program knows what its looking at.

Thank you for reading this please discuss your ideas,this idea would be really cool, however it would be completely different from bumptop and take a LOT of time.