I posted this question on signal processing stack exchange but no bites.
Normally intrinsic parameters are estimated using a pattern of a known size but unknown location. I don't understand how intrinsic parameters can be estimated from this alone since changing the focal length and changing the distance to the pattern result in an equivalent projected image. How do you address this unknown scale issue?
I looked at the paper Matlab cities in their camera calibration code but this wasn't directly addressed.
A pinhole camera is not the same as a orthographic one. Changing the focal length is not equivalent to changing the distance of the target from the camera, when the (planar) target is not parallel to the image plane. The perspective foreshortening changes.