The main requirement for satellite and airborne imagery exploitation is to make conform (overlay) images (optical, radar, infrared, etc) to a working geographic model that can be either a map or another reference image. The GEORIS tool method is to overlay accurately and image with any other image by using only the image contents. Operational image-analyst community dealing with crisis management and quick decision making has required this important operational constraint. Indeed, in operational near real time context, often-different images and maps shall be combined without knowledge on the sensor characteristics.

To solve the current registration polynomial method drawbacks, a new state of art technique as been designed and developed using a registration model which integrates ground control and tie points as well as recognised linear feature (road, power line, railway, pipe and water networks, bridge, building, shoreline, etc). Firstly linear features are used to calculate the polynomial model accuracy and estimate its residual quality. Secondly, the linear features are used to define a graph model including thousand of control points. Then a numerical process to match the graphs is used to optimise the best registration model.

For mountains areas or inaccurate maps, a polynomial model cannot be applied, even with a superior order. The developed GEORIS method proposes a multiple local fitting model approach. Such as technique has the advantage to take into account local relief and increase significantly the matching precision. To improve again the relative pixel positioning accuracy, the last GEORIS version is able to use a digital elevation model when available.

GEORIS software has been developed for WEU/SC (Western European Union), which used it in an operational framework. Georis is also used by JRC.

Contact:

Philippe Garneson
pg@acri-st.fr