We used PhotoModeler Pro 5 (Eos Systems Inc., 2006) for camera calibration. The calibration procedure consists of taking a minimum of eight photos of a calibration grid with the same camera settings as those used
during aerial photo acquisition. The modeled parameters are input into LPS, and are used during the aero
triangulation process. The radial distortion curve derived from the calculated coefficients shows the considerable distortion near the edge of the images, which explains the difficulties experienced during photogrammetric processing without those parameters.