Active Contour (or Snake) Model is recognized as one of the efficient tools for 2D/3D image segmentation. How- ever, traditional snake models prove to be limited in sev- eral aspects. The presentpaper describes a set of difision equations applied ro image gradient vectors, yielding a vec- torfeld over the image domain. The obtained vectorfield pmvides the Snake Model an exrernal force as well as an auromatic way to generate the initial contours. Finally a region merging technique is employed to further impmve the segmentation results.