A multi-sensor system for airborne image capture and georeferencing

The development and preliminary testing of a fully digital multi-sensor sys tem for airborne remote sensing and geographic information system (GIS) app lications is described. This system was developed at The University of Calg ary in collaboration with The University of California at Berkeley, with ai rcraft and logistics support by HJW Inc., California. it integrates a mediu m class inertial navigation system (INS), two low-cost Global Positioning S ystem (GPS) receivers, and a high-resolution digital camera. During aerial image capture, camera exposure stations and INS digital records are time-ta gged in real time by GPS. The INS/GPS-derived trajectory parameters describ e the rigid body motion of the carrier aircraft. Thus, they are directly re lated to the parameters of exterior orientation. During post processing, th ese parameters are extracted, eliminating the need for ground control for a irborne image acquisition applications. Flight tests were performed over a part of the university campus at Berkeley, using a strip photography approa ch to test the integrated system performance. In this paper, the concept of direct georeferencing of digital images without ground control is presente d. System calibration results are then discussed in some detail, and specia l attention is given to the geometrical analysis of the system imaging comp onent. An improved imaging system is proposed and validated by computer sim ulations. The potential of the new system for photogrammetric use is then d iscussed. The major applications of such a system will be in photo ecometri cs; the mapping of utility lines, roads, and pipelines; and the generation of digital elevation models for engineering applications.