在这个程序中采用线性插值的方法利用动态圆，在每一个节点上画圆，搜索到三个已知点后结束求出系数用来计算此节点的高程-In this program, linear interpolation method using dynamic circle, draw a circle at each node, the search to three known points, calculated after the end of the coefficient used to calculate the height of this node