After iterating several times, the control points were fitted as ellipse by least square method, which was sampled to be new initial boundary of the improved GVF model.

• 控点每迭代一定次数后，利用最小二乘原理，估算出椭圆准确位置，对椭圆边界采样作为新的初始轮廓，重新进行迭代，形成有约束形变。