Realtime Birds's eye view stream from IP cameras

I want to have an application that creates a real-time bird's eye view stream by using 4 - 6 regular IP cameras (or 4 fisheye cameras) around our store (monitoring purposes). Then the next step will be keeping track of each car in the parking lot and getting timestamps with respect to their locations. For example, timestamp of id:#5 car when it just stopped by the first window, second window...
And a total number of cars in the parking lot.