Tracking Rectangles

[yash101]

I have wanted to design a vision system to work like that and calculate the distance from the target without range sensors or any other sensors. I also wanted to skip the Kinect because of how hard it is to interface to the robot, and it's slow speed. This is exactly the routine that I wanted to do. Now, I know how to implement it. Thank You!
Also, if I am not wrong, does it follow the laws of perspective that explain how an image looks smaller as it is farther away from your eyes, in this case, the camera.

Here's and O: O
Look at it up close. doesn't it look large?
Now look at it five feet away. It should look much smaller now.
If I am not wrong, I think that is how this is supposed to work!