描述

以几何体的形式返回所提供几何体的双精度(浮点8)最小边界框。多边形由边界框的角点定义(( MINX ， MINY )、( MINX ， MAXY )、( MAXX ， MAXY )、( MAXX ， MINY )、( MINX ， MINY ))。(PostGIS将添加一个 ZMIN / ZMAX 也要协调)。

退化情况(垂直线、点)将返回低于以下维度的几何 POLYGON ，即。 POINT 或 LINESTRING 。

可用性：1.5.0行为更改为输出双精度，而不是浮动4

This method implements the OGC Simple Features Implementation Specification for SQL 1.1. s2.1.1.1

This method implements the SQL/MM specification. SQL-MM 3：5.1.15

示例

SELECT ST_AsText(ST_Envelope('POINT(1 3)'::geometry));
 st_astext
------------
 POINT(1 3)
(1 row)


SELECT ST_AsText(ST_Envelope('LINESTRING(0 0, 1 3)'::geometry));
                   st_astext
--------------------------------
 POLYGON((0 0,0 3,1 3,1 0,0 0))
(1 row)


SELECT ST_AsText(ST_Envelope('POLYGON((0 0, 0 1, 1.0000001 1, 1.0000001 0, 0 0))'::geometry));
                                                  st_astext
--------------------------------------------------------------
 POLYGON((0 0,0 1,1.00000011920929 1,1.00000011920929 0,0 0))
(1 row)
SELECT ST_AsText(ST_Envelope('POLYGON((0 0, 0 1, 1.0000000001 1, 1.0000000001 0, 0 0))'::geometry));
                                                  st_astext
--------------------------------------------------------------
 POLYGON((0 0,0 1,1.00000011920929 1,1.00000011920929 0,0 0))
(1 row)

SELECT Box3D(geom), Box2D(geom), ST_AsText(ST_Envelope(geom)) As envelopewkt
        FROM (SELECT 'POLYGON((0 0, 0 1000012333334.34545678, 1.0000001 1, 1.0000001 0, 0 0))'::geometry As geom) As foo;


        

点和线串的包络。

SELECT ST_AsText(ST_Envelope(
                ST_Collect(
                        ST_GeomFromText('LINESTRING(55 75,125 150)'),
                                ST_Point(20, 80))
                                )) As wktenv;
wktenv
-----------
POLYGON((20 75,20 150,125 150,125 75,20 75))

另请参阅

方框2D, Box3D, ST_OrientedEnvelope