编辑现在已将其移至gis特定网站here
运行以下查询:
SELECT ST_AsText(ST_ConcaveHull(ST_GeomFromText('MULTIPOINT(-0.211393 51.606972, -0.237981 51.624109, -0.237982 51.624104)',4326),0.99))
返回软错误:
POLYGON((-0 0,-0 0,-0 0,-0 0))
然而,如果我的纵向坐标从-0.999..0.999范围内向上(或向下)上升,那么它可以工作:
SELECT ST_AsText(ST_ConcaveHull(ST_GeomFromText('MULTIPOINT(-1.211393 51.606972, -1.237981 51.624109, -1.237982 51.624104)',4326),0.99))
给出
POLYGON((-1.211393 51.606972,-1.237982 51.624104,-1.237981 51.624109,-1.211393 51.606972))
这是怎么回事?!