A common way to use AR to enhance the world that's seen through the device's camera is to recognize a target image and either display a different or animation image in its place or to add a 3D model to the view that tracks the location of the image.
We'll do the latter in this recipe, making a 3D model appear over a book's cover image that we will add to a library:

Figure 15.86 – A 3D "car" model displayed above the book cover image in our AR phone app