Now that we know how to track planar objects, let's see how to overlay 3D objects on top of the real world. The objects are 3D but the video on our screen is 2D. So the first step here is to understand how to map those 3D objects to 2D surfaces so that it looks realistic. We just need to project those 3D points onto planar surfaces.
Once we estimate the pose, we project the points from the 3D to the 2D. Consider the following image:
As we can see here, the TV remote control is a 3D object but we are seeing it on a 2D plane. Now if we move it around, it will look like this:
This 3D object ...