This post shows how to read your phone camera and make it appears as transparent, aka to act as a see-through. It may seems unrelated to 3d at first but it is extremely useful in augmented reality. I know it may seem silly :) But this see-throught is the base of Augmented Reality in a phone. This and other AR tech will be the subject of future posts.
It makes your device ‘appears as transparent’ So when the user is looking at her device, she is seeing the reality. You just have to display your augmented part on top and you got augmented reality. A Picture is Worth a Thousand Words :)