@article{Denzler97:ARP,<br>  title = {Active Rays: Polar-transformed Active Contours for Real-Time Contour Tracking},<br>  journal = {Journal on Real-Time Imaging},<br>  author = {Joachim Denzler and Heinrich Niemann},<br>  year = {1997},<br>  pages = {(to appear)},<br>}<br>