AUTOMATIC TRACKING OF CREVASSES ON SATELLITE IMAGES

Measurements of glacier motion and deformation are obtained by automat ically matching features, such as crevasses, on repeat images. A compu ter-based method identifies and tracks groups of features on successiv e images, and calculates their displacement, and the rotation and dist ortion of the ice. Ice deformation within each matched area is permitt ed and calculated using a least-squares method within each area. The m ethod 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 metho d, similar to that used by Bindschadler and Scambos, also obtains very satisfactory results.