Aspects of direct georeferencing in photogrammetry

Abstract

Reliable and high-precision GNSS systems and inertial measurement units are playing increasingly important role in aerial surveying. As a result, direct georeferencing is receiving increasing attention in photogrammetry. In this case, exterior orientation elements of the images are available without measuring ground control points. Using this method, fast and near real-time photogrammetric processing can be implemented. Using exterior orientation parameters provided by inertial navigation systems, the direct georeferencing task can be fulfilled by solving an overdetermined system of equations, therefore we get an approximate solution. The system of equations can be solved by analytical method, but also by numerical method using iteration. This paper reviews the characteristics of direct georeferencing, typical measurement errors, and compares solution methods, analyzing their accuracy and computational needs using MATLAB.