설명

Creates a topogeometry object for layer denoted by layer_id and registers it in the relations table in the toponame schema.

tg_type is an integer: 1:[multi]point (punctal), 2:[multi]line (lineal), 3:[multi]poly (areal), 4:collection. layer_id is the layer id in the topology.layer table.

노드들의 집합이 점형 레이어를 형성하고, 경계선들의 집합이 선형 레이어를 형성하고, 표면들의 집합이 면형 레이어를 형성하며, 노드, 경계선, 표면의 혼합 집합이 도형 집합을 형성할 수 있습니다.

구성 요소 배열을 생략하면 텅 빈 TopoGeometry 객체를 생성합니다.

Availability: 1.1

예시: 기존 경계선으로부터 형성

Create a topogeom in ri_topo schema for layer 2 (our ri_roads), of type (2) LINE, for the first edge (we loaded in ST_CreateTopoGeo).

INSERT INTO ri.ri_roads(road_name, topo) VALUES('Unknown', topology.CreateTopoGeom('ri_topo',2,2,'{{1,2}}'::topology.topoelementarray);

예시: 면형 도형을 가장 잘 추측한 TopoGeometry로 변환

표면들의 집합으로 형성돼야 하는 도형을 가지고 있다고 해봅시다. 예를 들어 blockgroups 테이블이 있는데 각 블록 그룹의 TopoGeometry를 알고 싶습니다. 데이터가 완벽하게 정렬돼 있다면, 다음과 같이 할 수 있습니다:

-- create our topo geometry column --
SELECT topology.AddTopoGeometryColumn(
        'topo_boston',
        'boston', 'blockgroups', 'topo', 'POLYGON');

-- addtopgeometrycolumn --
1

-- update our column assuming
-- everything is perfectly aligned with our edges
UPDATE boston.blockgroups AS bg
        SET topo = topology.CreateTopoGeom('topo_boston'
        ,3,1
        , foo.bfaces)
FROM (SELECT b.gid,  topology.TopoElementArray_Agg(ARRAY[f.face_id,3]) As bfaces
        FROM boston.blockgroups As b
            INNER JOIN topo_boston.face As f ON b.geom && f.mbr
        WHERE ST_Covers(b.geom, topology.ST_GetFaceGeometry('topo_boston', f.face_id))
            GROUP BY b.gid) As foo
WHERE foo.gid = bg.gid;

--the world is rarely perfect allow for some error
--count the face if 50% of it falls
-- within what we think is our blockgroup boundary
UPDATE boston.blockgroups AS bg
        SET topo = topology.CreateTopoGeom('topo_boston'
        ,3,1
        , foo.bfaces)
FROM (SELECT b.gid,  topology.TopoElementArray_Agg(ARRAY[f.face_id,3]) As bfaces
        FROM boston.blockgroups As b
            INNER JOIN topo_boston.face As f ON b.geom && f.mbr
        WHERE ST_Covers(b.geom, topology.ST_GetFaceGeometry('topo_boston', f.face_id))
        OR
 (  ST_Intersects(b.geom, topology.ST_GetFaceGeometry('topo_boston', f.face_id))
            AND ST_Area(ST_Intersection(b.geom, topology.ST_GetFaceGeometry('topo_boston', f.face_id) ) ) >
                ST_Area(topology.ST_GetFaceGeometry('topo_boston', f.face_id))*0.5
                )
            GROUP BY b.gid) As foo
WHERE foo.gid = bg.gid;

-- and if we wanted to convert our topogeometry back
-- to a denormalized geometry aligned with our faces and edges
-- cast the topo to a geometry
-- The really cool thing is my new geometries
-- are now aligned with my tiger street centerlines
UPDATE boston.blockgroups SET new_geom = topo::geometry;

참고

AddTopoGeometryColumn, toTopoGeom ST_CreateTopoGeo, ST_GetFaceGeometry, TopoElementArray, TopoElementArray_Agg