Integrated Sensor Orientation Simulator

Aerial Triangulation (AT) has long been a solution to the determination of the Exterior Orientation (EO) of the camera, but it requires knowledge of ground control points which must still be established through ground surveying, which is both an expensive endeavor and impracticable for inaccessible areas or dangerous locations.

With the advancement of Micro-ElectroMechanical Systems (MEMS) and improvements in sensor technology, direct georeferencing have played an increasingly important role in many photogrammetric applications. The GPS/INS (Global Positioning System/Inertial Navigation System) enables real-time acquisition of imaging orientation parameters without post computational operations allowing to achieve considerable savings of both cost and time.

However, some researchers have shown the accuracy of direct georeferencing to be inferior to the results of conventional aerial triangulation . Another serious problem with direct georeferencing is that it results in large y-parallax in stereo models. Presently, the y-parallax problem may be addressed by implementing Integrated Sensor Orientation (ISO). ISO is another alternative approach to georeferencing that combines the advantages of direct georeferencing and aerial triangulation.

Since the inclusion of tie-points is a major contributing factor to the accuracy of ISO, the operators usually perform interactive post operations after automated tie-point selection to ensure the quality of tie-points. As, in this case, tie-points are nearly flawless, the operators may wonder how many tie-points are sufficient to refine the accuracy of the directly measured EOs, and how much the accuracy can be improved. Are the positions of tie-points significant and do the distribution of tie-points influence the adjustment result? The problem is more complicated when tie-points are subjected to contaminate with some outliers such as those tie-points produced for real-time applications, for example airborne multi-sensor rapid mapping systems or disaster monitoring systems. For said applications, tie-pionts must be produced in real-time and interactive quality check of tie-points is hardly possible. In this case, the accuracy of tie-points is still questionable. The question arises as to whether less accurate tie-points can still benefit the refinement of EOs. Can a large number of tie-points compensate for their less accuracy?

In an attempt to address the aforementioned problems, this work presents an implementation of an integrated sensor orientation simulator.

The below image presents a snapshot result of the simulator in generating the ground points and coverage for each image.

Publications:
1. Tanathong, S., Lee, I., 2014. Integrated sensor orientation simulator: design and implementation. European Journal of Remote Sensing, vol 47, pp 497 - 512. [Download paper]
2. Tanathong, S., Lee, I., 2012. A design framework for an integrated sensor orientation simulator. Proceedings of ISVC, Greece. [LINK]