1. A system for detecting and tracking a curvilinear object in a three-dimensional space, comprising: an image acquisition system comprising a video camera arranged to acquire a video image of said curvilinear object and output a corresponding video signal, said video image comprising a plurality n of image frames each at a respective time t i , where i=1, 2,. .. , n; and a data processing system adapted to communicate with said image acquisition system to receive said video signal, wherein said data processing system is configured to determine a position, orientation and shape of said curvilinear object in said three-dimensional space at each time t i by forming a computational model of said curvilinear object at each time t i such that a projection of said computation model of said curvilinear object at each time t i onto a corresponding frame of said plurality of image frames of said video image matches a curvilinear image in said frame to a predetermined accuracy to thereby detect and track said curvilinear object from time t 1 to time t n .