Each of the regular and irregular faces on the model is assigned a point value system which is then used within the processing interface.
Unlike smartphones or wearable AR, projected AR experiences are site specific. The source of the projection in relation to the canvas and position of the viewer needs to be accounted for.
How do you project a rectangle on one of the sides of a cube? It would be easy when the projector is exactly in front of the target side.
If the projector is not directly in front of the canvas then we will quickly observe a keystone effect. Simply speaking the image will be distorted.
To fix this, the vertices of the projected image are tweaked so that the projected image is distorted to look like the projector "sees" it; as demonstrated in the figure below.