A Semi-Automated Line Tracing Technique for Monitoring Ice Margins in Antarctic Images

The current shape and rate of change of the margins of the Antarctic ice sheet are poorly known. Since polar regions are inhospitable, remotely sensed images provide an invaluable data source for studying the ice margin. These images can be examined by a human expert or processed automatically by a computer. This paper describes the design and implementation of a semi-automated technique to trace ice margins in synthetic-aperture-radar images. The technique is based on a deformable contour model derived from the active contour model of Kass et.al. (1988) and the discrete dynamic contour of Lobregt & Viergever (1995). The contour is initialised by the user, to approximate the margin, and the deformation process causes the contour to accurately mold itself to the shape of the margin. The technique has been tested on a number of different images with acceptable results in most cases.