Question about Augmented Reality


I have found this document:

At the page 9, the equation (1), it is supposed we will find the values of Projection matrix, but…

from where do we take the values X1, Y1 and Z1?

Are these the values from the base of the pyramid (Pc, P1, P2 and P3) taking Pc as (0,0,0)?

You can help me also telling me some augmented reality forum. This below doesnt work: