Automatic tracking of crevasses on satellite images

Measurements of glacier motion and deformation are obtained by automatically matching features, such as crevasses, on repeat images. A computer-based method identifies and tracks groups of features on successive images, and calculates their displacement, and the rotation and distortion of the ice. Ice deformation within each matched area is permitted and calculated using a least-squares method within each area. The method is applied to SPOT satellite images of ice stream B, Antarctica. A quality-checking scheme rejects inappropriate matches. The results compare satisfactorily with velocities obtained by manual methods from repeat photography of the same region. A simpler version of the method, similar to that used by Bindschadler and Scambos, also obtains very satisfactory results.