Theoretical Accuracy of Direct Georeferencing with Position and Orientation System in Aerial Photogrammetry

According to the principle of space intersection、collinearity equations and error propagation law, mathematical models of theoretical accuracy of direct georeferencing are proposed in this paper. The validity and feasibility of the mathematical models are tested using four sets of actual photos at different scales and terrains. Results indicate that accuracy of direct georeferencing based on space intersection is in relation to photographic scale and accuracy of exterior orientation elements, while accuracy of direct georeferencing based on collinearity equations is only in relation to projective scale, but both accuracies have not clear relation to terrain. Theoretical accuracy of direct georeferencing based on collinearity equations is better than that based on space intersection, but practical accuracy of both methods are same basically and different from theoretical accuracy. Practical accuracy of direct georeferencing using exterior orientation elements obtained by the POS directly can satisfy the requirements of aerial photogrammetric topographic mapping of corresponding scale.