설명

Creates a Polygon or CurvePolygon formed by the given shell and optional array of holes. Input geometries must be closed LineStrings, CircularStrings, CompoundCurves, or NURBSCurves (rings). If any input ring is curved, the result is a CurvePolygon.

Variant 1: Accepts one shell ring.

Variant 2: Accepts a shell ring and an array of inner (hole) rings. A geometry array can be constructed using the PostgreSQL array_agg(), ARRAY[] or ARRAY() constructs.

This function supports 3d and will not drop the z-index.

Enhanced: 3.7.0 - Support for curved input rings was introduced.

예시: 배열 버전 사용하기

인코딩된 폴리라인 스트링으로부터 라인스트링을 생성합니다.

SELECT ST_MakePolygon(ST_GeomFromText('LINESTRING(75 29,77 29,77 29, 75 29)'));

Create a Polygon from an open LineString, using ST_StartPoint and ST_AddPoint to close it.

SELECT ST_MakePolygon(ST_AddPoint(foo.open_line, ST_StartPoint(foo.open_line)) )
FROM (
  SELECT ST_GeomFromText('LINESTRING(75 29,77 29,77 29, 75 29)') As open_line) As foo;

인코딩된 폴리라인 스트링으로부터 라인스트링을 생성합니다.

SELECT ST_AsEWKT(ST_MakePolygon('LINESTRING(75.15 29.53 1,77 29 1,77.6 29.5 1, 75.15 29.53 1)'));

POLYGON((75.15 29.53 1,77 29 1,77.6 29.5 1,75.15 29.53 1))

Create a Polygon from a LineString with measures

SELECT ST_AsEWKT(ST_MakePolygon('LINESTRINGM(75.15 29.53 1,77 29 1,77.6 29.5 2, 75.15 29.53 2)'));

POLYGONM((75.15 29.53 1,77 29 1,77.6 29.5 2,75.15 29.53 2))

Create a CurvePolygon from a CircularString shell.

SELECT ST_AsText(ST_MakePolygon('CIRCULARSTRING(0 0,1 1,2 0,1 -1,0 0)'));

CURVEPOLYGON(CIRCULARSTRING(0 0,1 1,2 0,1 -1,0 0))

예시: 내곽 구조를 가진 외곽 구조

개미 구멍을 가진 도넛을 빌드해봅시다.

SELECT ST_MakePolygon(
    ST_ExteriorRing(ST_Buffer(ring.line,10)),
    ARRAY[  ST_Translate(ring.line, 1, 1),
        ST_ExteriorRing(ST_Buffer(ST_Point(20,20),1)) ]
    )
FROM (SELECT ST_ExteriorRing(ST_Buffer(ST_Point(10,10),10,10)) AS line ) AS ring;

Create a set of province boundaries with holes representing lakes. The input is a table of province Polygons/MultiPolygons and a table of water linestrings. Lines forming lakes are determined by using ST_IsClosed. The province linework is extracted by using ST_Boundary. As required by ST_MakePolygon, the boundary is forced to be a single LineString by using ST_LineMerge. (However, note that if a province has more than one region or has islands this will produce an invalid polygon.) Using a LEFT JOIN ensures all provinces are included even if they have no lakes.

SELECT p.gid, p.province_name,
    CASE WHEN array_agg(w.geom) IS NULL
    THEN p.geom
    ELSE  ST_MakePolygon(
        ST_LineMerge(ST_Boundary(p.geom)),
        array_agg(w.geom)) END
FROM
    provinces p LEFT JOIN waterlines w
        ON (ST_Within(w.geom, p.geom) AND ST_IsClosed(w.geom))
GROUP BY p.gid, p.province_name, p.geom;

Another technique is to utilize a correlated subquery and the ARRAY() constructor that converts a row set to an array.

SELECT p.gid,  p.province_name,
    CASE WHEN EXISTS( SELECT w.geom
        FROM waterlines w
        WHERE ST_Within(w.geom, p.geom)
        AND ST_IsClosed(w.geom))
    THEN ST_MakePolygon(
        ST_LineMerge(ST_Boundary(p.geom)),
        ARRAY( SELECT w.geom
            FROM waterlines w
            WHERE ST_Within(w.geom, p.geom)
            AND ST_IsClosed(w.geom)))
    ELSE p.geom
    END AS geom
FROM provinces p;

참고

ST_BuildArea ST_Polygon