ST_AsMVTGeom_云原生数据库 PolarDB(PolarDB)-阿里云帮助中心

将一个地理网格对象转换为瓦片坐标系的几何对象。

语法

geometry ST_AsMVTGeom(geomgrid grid, geometry bounds, int4 extent, int4 buffer, boolean clip_geom);
geometry ST_AsMVTGeom(h3grid grid, geometry bounds, int4 extent, int4 buffer, boolean clip_geom);

返回值

经过坐标系转换的几何对象。

参数

参数名称	描述
grid	需要输出到MVT的geomgrid或h3地理网格对象。
bounds	瓦片的矩形边界，不包含缓冲区。
extent	瓦片坐标系中的瓦片大小，默认4096。
buffer	瓦片坐标系中的缓冲区大小，默认256。
clip_geom	grid对应的几何形状是否被瓦片边界裁剪，默认true。

描述

将地理网格对象对应的几何形状转换为瓦片坐标系的几何对象。
和常用的输入参数为Geometry的ST_AsMVTGeom函数不同，bounds的类型为Geometry，而非Box2D。
输出的坐标系由bounds决定，建议使用ST_TileEnvelope函数来生成bounds。
若使用ST_TileEnvelope函数以外的方法来生成bounds，需要设定SRID。

示例

select st_asmvtgeom('010200040000'::geomgrid, st_tileenvelope(0, 0, 0));

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 0103000020110F000001000000050000000000000000D8A2400000000000FC99400000000000D8A240000000000000A040000000000000A040000000000000A040000000000000A0400000000000FC99400000000000D8A2400000000000FC9940

select st_asmvtgeom('010200040000'::geomgrid, st_transform(st_tileenvelope(0, 0, 0), 4326));

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 0103000020E610000001000000050000000000000000D8A2400000000000F493400000000000D8A240000000000000A040000000000000A040000000000000A040000000000000A0400000000000F493400000000000D8A2400000000000F49340

select st_asmvtgeom('010200040000'::geomgrid, st_transform(st_tileenvelope(0, 0, 0), 4326), 1024, 128, false);

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 0103000020E610000001000000050000000000000000D882400000000000F073400000000000D8824000000000000080400000000000008040000000000000804000000000000080400000000000F073400000000000D882400000000000F07340

select st_asmvtgeom(st_h3fromlatlng(20.5, 128.2, 5), st_tileenvelope(0, 0, 0));


------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 0103000020110F00000100000006000000000000000064AB400000000000449C40000000000066AB400000000000489C40000000000066AB4000000000004C9C40000000000062AB4000000000004C9C40000000000062AB400000000000489C40000000000064AB400000000000449C40

select st_asmvtgeom(st_h3fromlatlng(20.5, 128.2, 5), 'SRID=4326;POLYGON((-180 -85,-180 85, 180 85, 180 -85, -180 -85))');


--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 0103000020E61000000100000007000000000000000064AB400000000000449840000000000066AB400000000000489840000000000066AB400000000000509840000000000064AB400000000000549840000000000062AB400000000000549840000000000062AB4000000000004C9840000000000064AB40000000000044984