Abstract: bstract Authors applied the active contour model from image domain to3D surface to represent the feature line on triangular surfaces‚and solved such problems as how to obtain the initial contour and how to define the feature energy term.First‚A tracing-projection algorithm is presented for obtaining the initial contour by linking the user-specified points.Then‚mean curvature that describes the local surface feature quite well is defined as the feature energy term.And the total energy of an active contour is computed.Finally‚the feature line is optimized to the energy-minimizing position by iterations.Experimental results demonstrate that the optimized feature line can smoothly capture the object features.