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UBC Theses and Dissertations

Real time coding of hand drawn curves Szeliski, Richard Stephen


This thesis examines some techniques for the real-time coding of hand drawn curves. These curves are drawn on a data tablet or other graphical input device. As they are drawn, they are coded for transmission over a digital link and reconstructed at a receiving terminal. The real time requirement allows this system to be used for instant graphical communications. One possible application is as a sketchpad facility to aid telephone conferencing. The techniques examined involve sending selected control points along the curve, and using an interpolating function for reconstruction. The interpolator used is the two dimensional parametric cubic spline. Several members of this class of functions are introduced and evaluated. An existing technique for generating the control points (subsampling) is reviewed, and a new shape dependant algorithm is proposed. Automated curve fitting based on information in the original curve is examined. Test runs are made using the various techniques, and conclusions drawn.

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