Question

我有一个线串：

    LINESTRING( -43.0965167 -22.8808585,-43.0980368 -22.8807975,-43.0986518
 -22.8807735,-43.0990955 -22.8807701,-43.0991492 -22.8807697,-43.1005956
 -22.8807353,-43.1013221 -22.8807107,-43.1016904 -22.8807003,-43.1019484
 -22.8806902,-43.1020398 -22.8806866,-43.102591 -22.8806801,-43.1029336
 -22.8806666,-43.1036051 -22.8806402,-43.1039349 -22.8806272,-43.1042967
 -22.880613,-43.1061912 -22.8805398 )

现在我可以选择远处的所有点＆＃34; x＆＃34;从这条线（围绕线）。我已经尝试Find the nearest points along the linestring in specified distance limit and order但没有成功（总是在像分发这样的盒子中占据很多分数）。这是我开始编写的一段代码：

select p.way,p.name from planet_osm_point p where ST_DWithin( 
    ST_Transform( theLineGeom, 4326), ST_Transform( p.way,4326 ), 0.9)
    limit 50;

Answer 1

我认为你得到了很多分数，因为ST_DWithin使用几何srid的单位来执行计算。

boolean ST_DWithin（几何g1，几何g2，双精度distance_of_srid）;

所以你从你的线串获得0.9度的所有点。

您可以使用

boolean ST_DWithin（geography gg1，geography gg2，double precision distance_meters）;

将几何转换为地理。

否则你可以使用另一个srid。

Answer 2

解决。我得到太多积分，因为限制太大了。如果我在路线附近有2个点并告诉查询给我前50个，那么48个点将远离线但在边界框内。这就是我看到box like distribution的原因。

select * from pointscanner('<geomRoute_WILL_BE_HERE>') where round(distance::numeric, 5) < 500 /* meters */

CREATE OR REPLACE FUNCTION public.pointscanner( IN routeGeometry text)
  RETURNS TABLE(way geometry, name text, distance double precision, tags hstore, operator text, admin_level text, z_order integer) AS
$BODY$
DECLARE 
    geomRoute geometry;
    routeBB box2d;
BEGIN
    geomRoute = ST_GeomFromText('MULTILINESTRING( 
        (-43.1761935 -22.90642,-43.1755606 -22.9064116,-43.1754828 -22.9064106,-43.1753675 -22.9064091),
        (-43.176696 -22.9064062,-43.1761935 -22.90642),(-43.176805 -22.9064027,-43.176696 -22.9064062),
        (-43.1776911 -22.9049927,-43.1776625 -22.9050849,-43.1775227 -22.9055527,-43.1775045 -22.9056041,-43.1774504 -22.9057582),
        (-43.1782012 -22.9036858,-43.1778613 -22.9045254,-43.1777841 -22.9047287,-43.1777446 -22.9048326,-43.1777179 -22.9049164,-43.1776911 -22.9049927),
        (-43.1772218 -22.9063929,-43.1771252 -22.9063944,-43.1771118 -22.9063946,-43.1769202 -22.9064008,-43.176805 -22.9064027),
        (-43.1774504 -22.9057582,-43.1773182 -22.9061373,-43.1772868 -22.9062205,-43.1772218 -22.9063929),
        (-43.1834587 -22.9028997,-43.1833984 -22.9028862,-43.1830022 -22.9027778,-43.1825446 -22.9026278,-43.1821151 -22.9024891,-43.1816491 -22.9023374,-43.1815912 -22.9023186,-43.1813461 -22.9022388),
        (-43.1793173 -22.901581,-43.1791549 -22.9015418,-43.179105 -22.9015365,-43.1790457 -22.9015482,-43.1790174 -22.9015689,-43.178994 -22.9016082),
        (-43.1788184 -22.9020931,-43.1786726 -22.9025241,-43.1786518 -22.9025769,-43.1786063 -22.9026931),
        (-43.1813461 -22.9022388,-43.1806028 -22.9019969,-43.1805417 -22.901977,-43.1799074 -22.9017705),
        (-43.1799074 -22.9017705,-43.1797658 -22.9017244,-43.1793732 -22.9015989,-43.1793173 -22.901581),
        (-43.178994 -22.9016082,-43.1788184 -22.9020931),(-43.1784337 -22.9031366,-43.1782012 -22.9036858),
        (-43.1786063 -22.9026931,-43.17848 -22.9030174,-43.178461 -22.9030662,-43.1784337 -22.9031366))',4326);

    routeBB := ST_Extent(geomRoute);

    RETURN QUERY
    SELECT pt.way, pt.name, ST_Distance( geomRoute, ST_Transform(pt.way,4326) ) * 111195 as distance, 
        pt.tags, pt.operator, pt.admin_level, pt.z_order 
    FROM planet_osm_point pt
    where routeBB && ST_Transform(pt.way,4326);

END; $BODY$
  LANGUAGE plpgsql VOLATILE

如何选择一条线附近的所有点？

2 个答案: