Evaluation of Geometric Elements of Repeat Station Imaging and Registration

Repeat station imaging (RSI) is an approach to precise aerial image registration and change detection. It involves planning and conducting aerial imaging flights such that the same sensor returns to the same imaging stations over time, replicating view geometry, and the resultant images are geometrically processed on a frame-by-frame basis. The objective of this paper is to elucidate and model the geometric elements associated with RSI capture and processing that influence the accuracy of co-registration. When each type of offset or difference in orientation is modeled separately, relative displacement of features in RSI pairs are linear functions of the varying orientation parameters and focal length, with the exception of an inverse square relationship with altitude above ground level; the combination of higher altitude and longer focal length reduces image displacements approximately in half. The average difference (bias) between modeled and measured parallax in ground dimensions is 0.1 m. Isolating the effects of orientation and offset factors is a useful first step towards developing a robust analytical model of the geometry of RSI pairs.