Rubber Snake: Implementation on Signed Distance Potential

The theory of active contour models based on energy minimization (snakes) provides a top-down mechanism for the segmentation and description of objects of interest in images. The active contour methods described hitherto do not incorporate in the potential eld the gradient orientation of image edge points, a characteristic as important in the classical segmentation techniques as gradient magnitude itself. Here we present a technique to include this information by constructing a Signed Distance Potential (SDP), on which we deene snake's external energy. Besides, in order to emphasize the role of the gradient magnitude in snake's behaviour, we formulate a multithresholding deformation scheme (MTDS), which makes the snake move as a rubber gure. Experiments using rubber snakes on bone segmentation in hand radiographs show a signiicant improvement compared to the classical snake's formulation.