Geometric Calibration of the Hasselblad H3d Medium Format Camera

The Hasselblad H3D digital camera, which is designed for professional studio shootings, is equipped with a 39 megapixel digital back. It would be desirable to use this very high geometric resolution in photogrammetric applications. Unfortunately, the digital back does not have a tight connection to the camera body. In addition, the unknown internal image processing algorithms and the autofocus lens make it difficult to obtain a reliable camera calibration. In this paper, we investigate whether the Hasselblad H3D camera can be calibrated for use in photogrammetric applications. Repeated calibrations were performed using a 2D (planar) target as well as a 3D test field. Results of the individual calibration projects are compared in order to analyze the stability of the camera over time. We also investigate if there is a fixed pattern of systematic image residuals (after removal of radial distortion), which could be described by a distortion grid. Software tools were developed for semi-automatic calibration using the MATLAB programming environment. This calibration software consists of a graphical user interface supporting automated and precise measurement of circular point targets, robust calculation of initial orientation parameters and bundle adjustment with self-calibration capabilities. The commercial software package PhotoModeler (Eos Systems Inc./Vancouver) was also used for comparison to derive calibration parameters based on the planar target. * Corresponding author.