我们正在使用Postgresql和PostGIS扩展.
经过谷歌搜索后我发现我们可以使用线串来实现这一点.我不完全确定这种方法是否会成功.
假设我有源和目的地的坐标.
var RouteCoordinates = [
{lat: 37.772,lng: -122.214},{lat: 21.291,lng: -157.821},{lat: -18.142,lng: 178.431},{lat: -27.467,lng: 153.027}
];
我需要将它存储为我的数据库中的线串.
如果一名乘客也在这条路线上行驶,但我们知道他的来源和目的地不会完全在我的线路中,但他们会在附近.
例如,半径约1km
正如您所看到的那样,我的源和目的地就是那条线.当我旅行时,我想挑选所有那些(源和目的地)靠近我的路线(特定半径范围内)的人
如果我想在特定半径范围内找到我的数据库中的特定位置,我将会这样查询
SELECT id,name,address,geom FROM Seattle_Starbucks WHERE ST_DWithin(geom,ST_MakePoint(-122.325959,47.625138)::geography,1000);
现在我可以实现我的解决方案,因为我刚接触postGIS有点令人困惑
>如何在DB中存储我的所有源和目标点
ANS：我需要使用此函数ST_MakeLine转换为linestring,然后存储,对吧？
>如何根据我的要求查询,如上所述
能否请您了解如何实现这一目标.非常感谢您的帮助.谢谢
I need to convert in to linestring using this function ST_MakeLine and
then store,right?
是的,要将多个点合并为LINESTRING,您可以使用ST_MakeLine：
SELECT ST_AsText(
ST_MakeLine(ARRAY[ST_MakePoint(-122.21,37.77),ST_MakePoint(-157.82,21.29),ST_MakePoint(178.43,-18.14),ST_MakePoint(153.02,-27.46)]));
st_astext
---------------------------------------------------------------------
LINESTRING(-122.21 37.77,-157.82 21.29,178.43 -18.14,153.02 -27.46)
(1 Zeile)
How to query that based on my requirement as I have mentioned above
在LINESTRING的每个点上创建一个缓冲区,并检查其中的其他几何形状.
首先,你必须使用ST_DumpPoints将你的路径LINESTRING分成POINT …
db=# SELECT ST_AsText((ST_DumpPoints('LINESTRING(-122.21 37.77,153.02 -27.46)'::GEOMETRY)).geom);
st_astext
----------------------
POINT(-122.21 37.77)
POINT(-157.82 21.29)
POINT(178.43 -18.14)
POINT(153.02 -27.46)
(4 Zeilen)
..然后使用ST_Buffer在每个点周围创建一个缓冲区. ST_Buffer返回一个几何图形,其中包含点(或任何其他几何类型)周围的区域.例如,取你的路线的第一个点(如果我没有切换x和y,它在旧金山的某个地方)POINT(-122.21 37.76)：
db=# SELECT ST_AsText(
ST_Buffer('POINT(-122.21 37.76)'::GEOMETRY,0.0001,'quad_segs=16'));
返回此几何：
POLYGON((-122.2099 37.76,-122.209900481527 37.759990198286,-122.209901921472 37.7599804909678,-122.209904305966 37.7599709715323,-122.209907612047 37.7599617316568,-122.209911807874 37.7599528603263,-122.209916853039 37.7599444429767,-122.209922698955 37.7599365606716,-122.209929289322 37.7599292893219,-122.209936560672 37.7599226989547,-122.209944442977 37.7599168530388,-122.209952860326 37.7599118078736,-122.209961731657 37.7599076120467,-122.209970971532 37.7599043059664,-122.209980490968 37.759901921472,-122.209990198286 37.7599004815273,-122.21 37.7599,-122.210009801714 37.7599004815273,-122.210019509032 37.759901921472,-122.210029028468 37.7599043059664,-122.210038268343 37.7599076120467,-122.210047139674 37.7599118078736,-122.210055557023 37.7599168530388,-122.210063439328 37.7599226989547,-122.210070710678 37.7599292893219,-122.210077301045 37.7599365606716,-122.210083146961 37.7599444429767,-122.210088192126 37.7599528603263,-122.210092387953 37.7599617316568,-122.210095694034 37.7599709715323,-122.210098078528 37.7599804909678,-122.210099518473 37.759990198286,-122.2101 37.76,-122.210099518473 37.760009801714,-122.210098078528 37.7600195090322,-122.210095694034 37.7600290284677,-122.210092387953 37.7600382683432,-122.210088192126 37.7600471396737,-122.210083146961 37.7600555570233,-122.210077301045 37.7600634393284,-122.210070710678 37.7600707106781,-122.210063439328 37.7600773010453,-122.210055557023 37.7600831469612,-122.210047139674 37.7600881921264,-122.210038268343 37.7600923879533,-122.210029028468 37.7600956940336,-122.210019509032 37.760098078528,-122.210009801714 37.7600995184727,-122.21 37.7601,-122.209990198286 37.7600995184727,-122.209980490968 37.760098078528,-122.209970971532 37.7600956940336,-122.209961731657 37.7600923879533,-122.209952860326 37.7600881921264,-122.209944442977 37.7600831469612,-122.209936560672 37.7600773010453,-122.209929289322 37.7600707106781,-122.209922698955 37.7600634393284,-122.209916853039 37.7600555570233,-122.209911807874 37.7600471396737,-122.209907612047 37.7600382683432,-122.209904305966 37.7600290284677,-122.209901921472 37.7600195090322,-122.209900481527 37.760009801714,-122.2099 37.76))
如果你想知道这个缓冲区的形状,请阅读answer.
使用此查询,您可以检查另一个几何是否在此缓冲区内(ST_Within)：
db=# SELECT
ST_Within('POINT(-122.21 37.76)'::GEOMETRY,ST_Buffer('POINT(-122.21 37.76)'::GEOMETRY,'quad_segs=16'));
st_within
-----------
t
(1 Zeile)
要把它们放在一起,你可以使用CTE(又名WITH子句)并写下这样的东西：
WITH j AS (
SELECT
(ST_DumpPoints('LINESTRING(-122.21 37.77,153.02 -27.46)'::GEOMETRY)).geom AS g)
SELECT id,geom
FROM Seattle_Starbucks
WHERE ST_Within(geom,ST_Buffer(j.g,'quad_segs=16'))
