ok.. many thanks.
FX it's ok(from the manual)
fx and fy coefficients are normally equal. They may be different if the pixels of recording media were
not square, which is a very rare case. If you know the focal length of the lens, physical dimension of the
optical sensor and size of picture in pixels you may easily calculate these coefficients as: fx = focal length
in mm * x-dimension of sensor in pixels / x-dimension of sensor in mm. Similar formula applies to fy.
But for CX and CY?
In Photomodeler I think are XP and YP. Ok? but in Photomodeler the unit is in mm. Is it the same unit of Photoscan?