On the performance of photogrammetric scanners

Scanners are necessary for retrieving digital information from analogue imagery. This paper discusses their geometric and radiometric performance, as input devices for softcopy photogrammetric systems. A classification and overview of scanners, their major technical characteristics, and their development over the last years are given. Some important scanner aspects, including illumination, dynamic range and quantisation bits, colour scanning, use of linear versus area CCDs, subsampling methods, scanning throughput and speed, and geometric and radiometric calibrations are presented. Thereby, different technological alternatives, their advantages and disadvantages are discussed.