https://jingyan.baidu.com/article/7e440953d0d7722fc1e2ef48.html
先生成排水管起点.shp和排水管终点.shp
排水管起始点.shp 减去 排水管终点.shp = 雨水口(排水户篦子入水口)
排水管终点.shp 减去 排水管起始点.shp = 排放口(出水口)