CreateTopoGeom
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名称

CreateTopoGeom — 从拓扑元素数组创建一个新的拓扑几何对象 - tg_type: 1:[多]点, 2:[多]线, 3:[多]多边形, 4:集合

大纲

topogeometry CreateTopoGeom(varchar toponame, integer tg_type, integer layer_id, topoelementarray tg_objs, bigint tg_id);

topogeometry CreateTopoGeom(varchar toponame, integer tg_type, integer layer_id);

Description

为由layer_id表示的图层创建一个拓扑几何对象，并将其注册到拓扑名称架构的关系表中。

tg_type 是一个整数：1：[多]点（点）、2：[多]线（线性）、3：[多]多边形（面）、4：集合。 layer_id 是topology.layer 表中的层id。

点状层由一组节点形成，线性层由一组边形成，区域层由一组面形成，集合可以由节点、边和面的混合形成。

省略组件数组会生成一个空的 TopoGeometry 对象。

可用性：1.1

示例

Form from existing edges.

在"ri_topo"模式中为"layer 2"（我们的"ri_roads"）创建一个拓扑几何对象，类型为(2) LINE，用于第一条边（我们在ST_CreateTopoGeo中加载的边）。

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

Convert an areal geometry to best guess topogeometry.

假设我们有应该由面的集合形成的几何形状。 例如，我们有块组表，并且想知道每个块组的拓扑几何形状。 如果我们的数据完全一致，我们可以这样做：

Create the topogeometry column.

Code
SELECT topology.AddTopoGeometryColumn(
'topo_boston',
'boston', 'blockgroups', 'topo', 'POLYGON');
栅格输出
1

Update the column assuming everything is perfectly aligned with the edges.

Code
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, so this version allows some error. It counts a face if 50 percent of it falls within the expected block group boundary.

Code
WITH candidate_faces AS (
    SELECT
        b.gid,
        b.geom AS block_geom,
        f.face_id,
        topology.ST_GetFaceGeometry('topo_boston', f.face_id) AS face_geom
    FROM boston.blockgroups AS b
    INNER JOIN topo_boston.face AS f
        ON b.geom && f.mbr
),
block_faces AS (
    SELECT
        gid,
        topology.TopoElementArray_Agg(ARRAY[face_id, 3]) AS bfaces
    FROM candidate_faces
    WHERE ST_Covers(block_geom, face_geom)
        OR (
            ST_Intersects(block_geom, face_geom)
            AND ST_Area(ST_Intersection(block_geom, face_geom))
                
> ST_Area(face_geom) * 0.5
        )
    GROUP BY gid
)
UPDATE boston.blockgroups AS bg
SET topo = topology.CreateTopoGeom(
    'topo_boston',
    3,
    1,
    block_faces.bfaces
)
FROM block_faces
WHERE block_faces.gid = bg.gid;

To convert the topogeometry back to a denormalized geometry aligned with faces and edges, cast the topogeometry to a geometry. The resulting geometries are aligned with the TIGER street centerlines.

Code
UPDATE boston.blockgroups SET new_geom = topo::geometry;