PhotoModeler uses a standard lens distortion formulation with four parameters as seen in the Camera Viewer Dialog. The following formulas describe how PhotoModeler applies the distortion corrections. You do not need to follow nor understand this section unless you are trying to convert a PhotoModeler camera calibration for use with another program or convert another calibration for use with PhotoModeler.
Lens distortion causes a point's image on the imaging surface (film or ccd) to be shifted from its true position as if it had been imaged by an ideal pin-hole camera. The compensation for any point (x,y) on the image surface (given the principal point is (0,0)) is given by:
xc = x + drx + dpx
yc = y + dry + dpy
where xc,yc is the corrected image point,
drx is the x component of the radial lens distortion correction,
dry is the y component of the radial lens distortion correction,
dpx is the x component of the decentering lens distortion correction, and
dpy is the y component of the decentering lens distortion correction.