1 | initial version |
Well, cx and cy should be width/2 and height/2 respectively.
How did you generate them? Is it just perfectly flat, square image? Or did you do any perspective transforms?
If you have a perfectly flat, square marker, then just figure out how wide the marker should be (in a length unit such as inches or meters), how wide it is (in pixels), and how far you want it to be from the camera (in the same length unit).
You use the distance and width to figure out what the angle of the markers is, then from there figure out what the whole camera Field of View (FOV) is. Then you use the equation HERE (The horizontal one if you're using width) with h = number of columns in the image. That gives you f.