I need to generate a camera calibration pattern. Cameras are expected to be placed at an average height of 15 to 30 feet above ground pointing downwards at roughly 30 degrees. These cameras are deployed in open spaced monitoring different types of movement. During installation, operators often make mistakes when entering camera height and angle information into our system.
The objective is to get a sense of the ground plane and to be able to calculate how close or far objects are relative to their size.
The only automated option I could think of was to have operators use a camera calibration pattern that have been printed on a large paper. The pattern image will be a simple black and white checkerboard with a constant number of rows and columns (let's say 10). The problem is, I will not know in advance what size the printed image is.
The variables are:
- Height of the camera.
- Angle of the camera to the ground.
- Distance to pattern image.
- Size of the pattern image.
How can I determine the size of the pattern image while analyzing (which will allow me to scale other objects in a relative way).
Is there a better way to approach this problem?