ST_ASENCODEDPOLYLINE

📄字数 934

👁️阅读量 加载中...

功能描述

以编码折线形式返回几何图形。

语法格式

CLOB ST_ASENCODEDPOLYLINE(GEOMETRY geom, INTEGER precision=5);

参数说明

• geom：目标 GEOMETRY 对象。
• precision：精度，指定编码折线中将保留多少个小数位。可选，默认 5。

函数返回类型

CLOB 类型

使用说明

1. 此格式由精度为 5 的 Google 地图和精度为 5 和 6 的开源路由机使用。
2. 编码和解码时的值应该相同，否则坐标将不正确。

示例

基础使用：

SQL> SELECT ST_ASENCODEDPOLYLINE(GEOMFROMEWKT('SRID=4326;LINESTRING(-120.2 38.5,-120.95 40.7,-126.453 43.252)'));

+-----------------------------+
|            EXPR1            |
+-----------------------------+
| _p~iF~ps|U_ulLnnqC_mqNvxq`@ |
+-----------------------------+

(1 row)

与地理线串和地理分段结合使用，并放在谷歌地图上：

-- the SQL for Boston to San Francisco, segments every 100 KM
SQL> SELECT ST_ASENCODEDPOLYLINE(
                     ST_SEGMENTIZE(
                             ST_GEOGFROMTEXT('LINESTRING(-71.0519 42.4935,-122.4483 37.64)'),
                                     100000)::GEOMETRY) As encodedFlightPath;

+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|                                                                                                                                                                                                                                     ENCODEDFLIGHTPATH                                                                                                                                                                                                                                     |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| kojbGjitpLonTt_~CijSfq~C{eR|a_DiaQvq_Dk|Ov``DgwNvn`D_rMz{`DolL`haDyfKfsaDaaJl}aD_{HtfbD_uGznbDunF`vbDmhEb|bD_bDfacDq{BdecD_uAdhcDon@~icD{GxjcDr\njcDfcAdicDxiBtfcDfpCdccDvvDr~bD`}E~xbDhcGhrbDniHpjbDnoIzabDjuJ`xaDd{KhmaDt`MraaDbfN|t`DfkOhg`DhpPxx_D~tQhi_DpyR`y~Cx}Szg~CzaU|u}CpeVdc}C`iWto|CdlXj{{C`oYlf{CrqZvpzCzs[nzyCtu\pcyChw]`lxCnx^~swCjy_@j{vCxy`@fbvC~ya@vhuCvyb@tntCbyc@htsC`xd@nyrCvve@j~qC|tf@zbqCvrg@dgpCdph@bkoCdmi@|nnCzij@lrmC`fk@xulCzal@~xkCh}l@b|jChxm@`_jC|rn@~aiC |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

(1 row)