USGS/OSU progress with digital camera in situ calibration methods

The United States Geological Survey (USGS) in cooperation with The Ohio State University (OSU) and Calgary University (CU) have developed procedures and software for the efficient calibration of metric quality aerial cameras; both film- and CCD-based sensors. With the advent of the Global Positioning System (GPS), and its efficient use to position the exposure station of the aerial camera, it became necessary to accurately establish camera interior orientation under operational circumstances (in situ calibration) to assure agreement of the photogrammetric procedure results with positional data provided by GPS. Disagreement between photogrammetric resection methods, based on laboratory calibration, and GPS results were consistently as large as one part in 1000 of the flight height. This paper describes the development of the airborne method of camera calibration, software development, and some results of accuracy improvements when using the in situ method of camera calibration.