缓冲分析实现选中的一组或一类地图要素（点、线或面）按设定的距离条件，围绕其要素而形成一定缓冲区多边形实体，从而实现数据在二维空间得以扩展的信息分析方法-Buffer analysis selected one of a group or class map elements (point, line or surface) according to set distance conditions, focusing on the elements and the formation of a c