Hopefully I have this in the correct place, but apologies if not. What I'm trying to do is given I know the pixel that I am measuring to, how would I find the x, y and z co-ordinates of that pixel relative to the camera in millimeters, given that I have the focal length, width of the sensor and height of the sensor from the centre of the image? Those three things are all in mm.
For example: focal length is 50.0mm, sensor width is 23.4mm, and height of the sensor from the image is 15.6mm, how would I determine x, y and z? x and y are in parallel and in the same direction as the x and y axis of the image, and z is the distance from the camera to the pixel.
Any help would be appreciated! Also perhaps worth noting is that the object is a playing card, so I suppose the size of it would be relatively constant if that were needed.