Study of Stability Analysis of the Interior Orientation Parameters from the Small-format Digital Camera Using On-the-job Calibration

Small and medium format digital cameras are widely used in Photogrammetric applications due to their accessibility, availability and quick image acquisition and processing. In addition, the resolution of these cameras has significantly increased while their prices decreased. Generally, a small-format digital camera does not have a pre-definition of the internal geometric characteristics, commonly known as the interior orientation parameters (IOPs), which are computed by a bundle adjustment with a self-calibration procedure that uses a set of images, geometrically acquired over the calibration test field. However, to extract precise and reliable 3D metric information from images, an important condition should be considered: are the interior orientation parameters accurate enough for photogrammetric applications? Usually, the camera calibration procedure is performed using a target or a linear test field, regardless of the photogrammetric project that will be performed later. For photogrammetric applications, the camera should be stable and the interior orientation parameters should not vary over time. Considering airborne photogrammetric mapping, the digital camera is exposed to different conditions from the ones registered during the terrestrial calibration procedure. Two aspects should be discussed: Do the interior orientation parameters change? Do the changes modify the quality of the derived information? In this paper we try to answer these questions. The digital camera Kodak DCS Pro 14n is calibrated under different conditions to determine the geometric stability of the Interior Orientation Parameters. Using traditional terrestrial calibration and airborne (on-the-job) calibration procedures, the camera is calibrated in two different situations. Mathematic correlations of interior orientation parameters within themselves and with exterior orientation parameters are examined and discussed. Two external target test fields are used to perform all experiments. The geometric stability for the camera is presented and discussed. Airborne photogrammetric experiments, using different sets of interior orientation parameters, are performed to verify the precision of 3D object position at different calibration process. Finally some conclusions are drawn from the experimental results, and future recommendations are proposed. * Corresponding author.