PostGIS - 路线匹配解决方案

Question

我们正在建立一个应用程序,我是一名司机,我从A点到B点旅行.在我的路上,我可以找到以相同路线旅行的乘客.

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}
    ];

我需要将其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(在特定半径范围内)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

1. 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？

2. 如上所述,如何根据我的要求查询

能否请您告诉我如何实现这一目标.非常感谢您的帮助.谢谢

Answer 1

关于你的问题的一些想法：

我需要使用此函数 ST_MakeLine 转换为线串然后存储，对吗？

是的，要将多个点合并为一个，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)

如何根据我上面提到的要求进行查询

在每个点上创建一个缓冲区LINESTRING，并检查其他几何图形是否在其中。

首先，你必须使用...将你的路由LINESTRING分成POINTs 。ST_DumpPoints

db=# SELECT ST_AsText((ST_DumpPoints('LINESTRING(-122.21 37.77,-157.82 21.29,178.43 -18.14,153.02 -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)

..然后用于ST_Buffer在每个点周围创建一个缓冲区。ST_Buffer 返回点周围区域的几何图形（或任何其他几何类型）。例如，采取路线的第一个点（如果我没有切换x和y，它位于旧金山的某个地方）POINT(-122.21 37.76)：

db=# SELECT ST_AsText(                                                         
       ST_Buffer('POINT(-122.21 37.76)'::GEOMETRY,0.0001, 'quad_segs=16'));

返回此几何图形：

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))

如果您想知道此缓冲区的形状，请阅读此答案。

使用此查询，您可以检查另一个几何图形是否在此缓冲区内 ( ST_Within)：

db=# SELECT
       ST_Within('POINT(-122.21 37.76)'::GEOMETRY,
          ST_Buffer('POINT(-122.21 37.76)'::GEOMETRY,0.0001, 'quad_segs=16'));
 st_within 
-----------
 t
(1 Zeile)

为了将它们放在一起，您可以使用CTE（又名WITH子句）并编写如下内容：

WITH j AS (
  SELECT
    (ST_DumpPoints('LINESTRING(-122.21 37.77,-157.82 21.29,178.43 -18.14,153.02 -27.46)'::GEOMETRY)).geom AS g)
SELECT id, name, address, geom
FROM Seattle_Starbucks
WHERE ST_Within(geom,ST_Buffer(j.g,0.0001, 'quad_segs=16'))