Geopositioning from high-resolution satellite imagery: experiences with the affine sensor orientation model

Sensor orientation based on a 3D affine transformation is appealing for high-resolution satellite imagery for three reasons: 1) Narrow-angle imaging sensors can be characterised by a skew parallel projection, 2) the affine model is linear, and 3) it is a straightforward computational model requiring a minimum of only four ground control points. Application of the affine model with Ikonos imagery has produced sub-pixel 3D geopositioning accuracy. In spite of this, there remain questions about the fidelity of the model where the area covered is large and where there is a significant terrain height variation. This paper describes the application of the affine model to multi-scene Ikonos stereo imagery covering large block areas. It is shown that area is not a factor influencing the impressive metric performance of the affine for pixel-level geopositioning.