使用pgrouting进行最短路径搜索

时间：2022-03-28 20:20:58
   PgRouting是基于开源空间数据库PostGIS用于网络分析的扩展模块，最初它被称作pgDijkstra，因为它只是利用Dijkstra算法实现最短路径搜索，之后慢慢添加了其他的路径分析算法，如A算法，双向A算法，Dijkstra算法，双向Dijkstra算法，tsp货郎担算法等，然后被更名为pgRouting。该扩展库依托PostGIS自身的gist索引，丰富的坐标系与图形类型，强大的几何处理能力，如空间查询，空间处理，线性参考等优势，能保障在较大数据级别下的网络分析效果更快更好。
最新源码见：
1、环境搭建
需要先安装PostgreSQL9.6，再安装PostGIS，注意版本号PostGIS2.4后已经集成了pgRouting，无需单独安装
PostGIS 官网 http://www.postgis.org/
pgRouting官网http://pgrouting.org/documentation.html
2、启用pgRouting功能，连接到对应postgres数据库后执行下面的sql语句
CREATE EXTENSION postgis;

CREATE EXTENSION pgrouting;
3、路网数据处理
由于路网分析的特殊性，只支持LineString类型，不支持MultiLineString类型，如果路网数据为MultiLineString类型导入前需加工处理，可使用arcgis在交叉点处使用打断相交线来分割线，参见
http://resources.arcgis.com/zh-cn/help/main/10.1/index.html#//01m8，最终可用的数据必须为路网不自相交，导入时选择简单的线类型，否则网络拓扑计算数据会错误
 
使用pgrouting进行最短路径搜索
4、路网拓扑数据计算处理，执行成功后，执行成功后会生产一个**_vertices_pgr的表，里面包含路网相交点的空间数据
 alter table road add column source int;

alter table road add column target int;

create index road_source_idx on road("source");

create index road_target_idx on road("target");

ALTER TABLE road  ADD COLUMN length double precision;  

SELECT pgr_createTopology('road',0.00001, 'geom', 'gid');  

update road set length =st_length(geom);

5、查询最短路径sql语句

SELECT seq, id1 AS node, id2 AS edge, cost,geom  FROM pgr_dijkstra('

SELECT gid AS id,

source::integer,

target::integer,

length::double precision AS cost

FROM xmpark_road',

1, 10, false, false) as di

join xmpark_road pt

on di.id2 = pt.gid

6、参数化的查询sql语句，可以用下面的语句，在geoserver中使用发布sql视图图层来显示导航搜索图层，见下图

SELECT seq, id1 AS node, id2 AS edge, cost,geom  FROM pgr_dijkstra('

SELECT gid AS id,

source::integer,

target::integer,

length::double precision AS cost

FROM xmpark_road',

%a%, %b%, false, false) as di

join xmpark_road pt

on di.id2 = pt.gid

使用pgrouting进行最短路径搜索

 7、在ol中使用上面发布的搜索图层使用起止交叉点来显示导航路径，源码如下
 <!DOCTYPE html>

 <html>

 <head>

 <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>

     <title></title>

     <meta http-equiv="X-UA-Compatible" content="IE=edge">

     <meta name="viewport" content="width=device-width,initial-scale=1.0,user-scalable=no" />

     <link rel="stylesheet" href="ol/ol.css" type="text/css">

     <script src="ol/ol-debug.js"></script>

     <script src="ol/proj4.js"></script>

     <script src="js/jquery-1.8.0.min.js"></script>

     <meta charset="utf-8" />

 </head>

 <body>

     <div id="map" style="width: 100%;height:800px;border:solid 1px red" class="map">

         <div>

             id1: <input id="id1" value="30" />

             id2: <input id="id2" value="66" />

             <input type="button" value="query" onclick="queryRoute()" />

         </div>

     </div>

 </body>

 </html>

 <script type="text/javascript">

     var format = 'image/png';

     var bounds = [501369.9375, 2494100.25,

         502073, 2495256.25];

     var mousePositionControl = new ol.control.MousePosition({

         className: 'custom-mouse-position',

         target: document.getElementById('location'),

         coordinateFormat: ol.coordinate.createStringXY(5),

         undefinedHTML: '&nbsp;'

     });

     var tiled = new ol.layer.Tile({

         visible: true,

         source: new ol.source.TileWMS({

             url: 'http://localhost:8080/geoserver/pg_ws/wms',

             params: {

                 'FORMAT': format,

                 'VERSION': '1.1.1',

                 tiled: true,

                 STYLES: '',

                 LAYERS: 'pg_ws:xmpark_road',

             }

         })

     });

     var cross_tiled = new ol.layer.Tile({

         //visible: true,

         source: new ol.source.TileWMS({

             url: 'http://localhost:8080/geoserver/pg_ws/wms',

             params: {

                 'FORMAT': format,

                 'VERSION': '1.1.1',

                 tiled: true,

                 STYLES: '',

                 LAYERS: 'pg_ws:xmpark_road_vertices_pgr',

             }

         })

     });

     var projection = new ol.proj.Projection({

         code: 'EPSG:3857',

         units: 'm',

         axisOrientation: 'neu',

         global: true

     });

     var map = new ol.Map({

         controls: ol.control.defaults({

             attribution: false

         }).extend([mousePositionControl]),

         target: 'map',

         layers: [

             tiled, cross_tiled

         ],

         view: new ol.View({

             projection: projection

         })

     });

     map.getView().fit(bounds, map.getSize());

     var routeLayer = null;

     function queryRoute() {

         if (routeLayer != null) {

             map.removeLayer(routeLayer);

         }

         var val1 = $("#id1").val();

         var val2 = $("#id2").val();

          routeLayer = new ol.layer.Tile({

             visible: true,

             source: new ol.source.TileWMS({

                 url: 'http://localhost:8080/geoserver/pg_ws/wms',

                 params: {

                     'FORMAT': format,

                     'VERSION': '1.1.1',

                     tiled: true,

                     STYLES: '',

                     LAYERS: 'pg_ws:xmpark_road_route',

                     'viewparams': 'a:' + val1 + ';b:' + val2

                 }

             })

         });

         map.addLayer(routeLayer);

     }

 </script>

导航图层搜索

最终实现效果如下：

使用pgrouting进行最短路径搜索

 
 
 

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