Assessing the Performance of Different Large Format Digital Cameras by Investigating the Geometric Accuracy and Camera Calibration

Abstract

This paper provides an independent investigation on the geometric accuracy and camera calibration of the new photogrammetric digital airborne camera systems, undertaken as a part of the German Society of Photogrammetry, Remote Sensing and Geoinfirmation (DGPF) project for investigating large format digital cameras (Vexcel Imaging UltraCamX, Z/I Imaging DMC and Z/I Imaging RMC Top 15). This paper presents results from the imaging data on 6 different flight days flown over a test site in Germany during a 10 week time window starting at the beginning of July till the middle of September 2008. Most of the sensors were flown at two different flying heights, resulting in two blocks with different Ground Sampling Distances (GSD); namely GSD 20cm and GSD 8cm. In this paper, the digital camera calibration was assessed through analyzing and identifying any systematic patterns in the image residuals. A new calibration method was undertaken in this paper based on analyzing the systematic errors of the high and low flown residuals. The bundle adjustment will be re-computed based on the analysis of the systematic residual patterns. This approach is based on analyzing the systematic errors of the high flown residuals and re-computing the bundle adjustment of the low flown images based on the residual corrections of the high flown images. These corrections were computed from a block triangulation and applied because the systematic patterns were considered similar for all images. The bundle adjustment will be re-computed based on the analysis of the systematic residual patterns. This approach is based on analyzing the systematic errors of the high flown residuals and re-computing the bundle adjustment of the low flown images based on the residual corrections of the high flown images. The results introduced in this paper were significantly improved by using the traditional existing selfcalibration method and the new calibration approach