postgresql - PostGIS - 路线匹配解决方案

Question

我们正在构建一个应用程序，我是一名司机，我从 A 点行驶到 B 点。在途中，我可以找到沿相同路线行驶的乘客。

我们正在使用带有 PostGIS 扩展的 PostgreSQL。

经过大量谷歌搜索后，我发现我们可以使用线串来实现这一点。我不确定这种方法是否可行。

假设我有起点和终点的坐标。

    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}
    ];

我需要将其作为线串存储在我的数据库中。

在确定乘客是否也在这条路线上行驶之后，但据我们所知，他的出发地和目的地不会完全在我的线路字符串中，但它们会在附近。例如半径 1 公里左右

如您所见，我的来源和目的地就是那条线。当我旅行时，我想选择所有(源和目的地)靠近我的路线(在特定半径内)的人

如果我想在我的数据库中找到特定半径内的特定位置，我将像这样查询

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，因为我是 postGIS 的新手，它有点令人困惑

1. 如何将我所有的源点和目标点存储在数据库中

ANS:我需要使用这个函数 ST_MakeLine 转换成线串然后存储，对吗？

1. 如何根据我上面提到的要求查询它

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:

I need to convert in to linestring using this function ST_MakeLine and then store, right?

是的，要将多个点合并到一个 LINESTRING 中，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，并检查是否有其他几何图形在其中。

首先，您必须使用 ST_DumpPoints 将您的路线 LINESTRING 拆分为 POINT ...

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，其中包含您的点周围的区域(或任何其他几何类型)。例如，取你路线的第一个点(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'));

返回这个几何体:

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))

如果您想了解此缓冲区的形状，请阅读此 answer .

并且使用此查询，您可以检查此缓冲区内是否有另一个几何体 (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)

要将它们放在一起，您可以使用 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,-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'))