一、软件安装
GeoServer下载地址:
http://geoserver.org/download/
PostgreSQL下载地址:
https://www.postgresql.org/download/
paAdmin3下载地址:
https://www.pgadmin.org/download/pgadmin-3-windows/
PostGIS下载地址:
http://postgis.net/windows_downloads/
pgRouting已经包含在安装程序中。
所有下载程序如下:
安装过程不再详述。
二、数据制作
我使用的是ArcMap来绘制路网数据,也可以使用其它的GIS软件,但好像没有这么方便,地理坐标系使用GCS_WGS_1984,编号为:4326。
注意:所有线段连接的地方都需要断开,这样便于以后的分析。
三、数据处理
使用paAdmin3连接PostgreSQL,并执行以下语句,在新的空间数据库里添加空间扩展:
CREATE EXTENSION postgis;
CREATE EXTENSION pgrouting;
CREATE EXTENSION postgis_topology;
CREATE EXTENSION fuzzystrmatch;
CREATE EXTENSION postgis_tiger_geocoder;
CREATE EXTENSION address_standardizer;
制作完路网数据后,需要使用 来把路网数据导入到PostgreSQL中去。
点击“View connection details….”在弹出的窗口中填入PostgreSQL的账号和密码,以及Database。
连接成功后,需要设置一下“Optionns…”
需要使用GBK编码,并勾选最下面一个选项。
添加路网数据,并设置SRID为:4326
导入完成后,会在数据库中创建一个对应的表:
在查询表中分别执行下列SQL,对表结构进行修改:
1.修改表结构
–添加起点id
ALTER TABLE public.road_xblk ADD COLUMN source integer;
–添加终点id
ALTER TABLE public.road_xblk ADD COLUMN target integer;
–添加道路权重值
ALTER TABLE public.road_xblk ADD COLUMN length double precision
2.创建拓扑结构
–为sampledata表创建拓扑布局,即为source和target字段赋值
SELECT pgr_createTopology(‘public.road_xblk’,0.0001, ‘geom’, ‘gid’);
3.创建索引
–为source和target字段创建索引
CREATE INDEX source_idx ON road_xblk(“source”);
CREATE INDEX target_idx ON road_xblk(“target”);
4.给长度赋值
–为length赋值
update road_xblk set length =st_length(geom);
–为road_xblk表添加reverse_cost字段并用length的值赋值
ALTER TABLE road_xblk ADD COLUMN reverse_cost double precision;
UPDATE road_xblk SET reverse_cost =length;
5.创建最短路径函数
—创建查询随意两点之前的最短路径的函数(新建查询-运行)
DROP FUNCTION pgr_fromAtoB(tbl varchar,startx float, starty float,endx float,endy float);
CREATE OR REPLACE function pgr_fromAtoB(tbl varchar,startx float, starty float,endx float,endy float)
returns geometry as
$body$
declare
v_startLine geometry;–离起点最近的线
v_endLine geometry;–离终点最近的线
v_startTarget integer;–距离起点最近线的终点
v_startSource integer;
v_endSource integer;–距离终点最近线的起点
v_endTarget integer;
v_statpoint geometry;–在v_startLine上距离起点最近的点
v_endpoint geometry;–在v_endLine上距离终点最近的点
v_res geometry;–最短路径分析结果
v_res_a geometry;
v_res_b geometry;
v_res_c geometry;
v_res_d geometry;
v_perStart float;–v_statpoint在v_res上的百分比
v_perEnd float;–v_endpoint在v_res上的百分比
v_shPath_se geometry;–开始到结束
v_shPath_es geometry;–结束到开始
v_shPath geometry;–最终结果
tempnode float;
begin
–查询离起点最近的线
execute ‘select geom, source, target from ‘ ||tbl||
‘ where ST_DWithin(geom,ST_Geometryfromtext(”point(‘|| startx ||’ ‘ || starty||’)”,4326),15)
order by ST_Distance(geom,ST_GeometryFromText(”point(‘|| startx ||’ ‘|| starty ||’)”,4326)) limit 1′
into v_startLine, v_startSource ,v_startTarget;
–查询离终点最近的线
execute ‘select geom, source, target from ‘ ||tbl||
‘ where ST_DWithin(geom,ST_Geometryfromtext(”point(‘|| endx || ‘ ‘ || endy ||’)”,4326),15)
order by ST_Distance(geom,ST_GeometryFromText(”point(‘|| endx ||’ ‘ || endy ||’)”,4326)) limit 1′
into v_endLine, v_endSource,v_endTarget;
–如果没找到最近的线,就返回null
if (v_startLine is null) or (v_endLine is null) then
return null;
end if ;
select ST_ClosestPoint(v_startLine, ST_Geometryfromtext(‘point(‘|| startx ||’ ‘ || starty ||’)’,4326)) into v_statpoint;
select ST_ClosestPoint(v_endLine, ST_GeometryFromText(‘point(‘|| endx ||’ ‘ || endy ||’)’,4326)) into v_endpoint;
— ST_Distance
–从开始的起点到结束的起点最短路径
execute ‘SELECT st_linemerge(st_union(b.geom)) ‘ ||
‘FROM pgr_kdijkstraPath(
”SELECT gid as id, source, target, length as cost FROM ‘ || tbl ||”’,’
||v_startSource || ‘, ‘ ||’array[‘||v_endSource||’] , false, false
) a, ‘
|| tbl || ‘ b
WHERE a.id3=b.gid
GROUP by id1
ORDER by id1’ into v_res ;
–从开始的终点到结束的起点最短路径
execute ‘SELECT st_linemerge(st_union(b.geom)) ‘ ||
‘FROM pgr_kdijkstraPath(
”SELECT gid as id, source, target, length as cost FROM ‘ || tbl ||”’,’
||v_startTarget || ‘, ‘ ||’array[‘||v_endSource||’] , false, false
) a, ‘
|| tbl || ‘ b
WHERE a.id3=b.gid
GROUP by id1
ORDER by id1’ into v_res_b ;
–从开始的起点到结束的终点最短路径
execute ‘SELECT st_linemerge(st_union(b.geom)) ‘ ||
‘FROM pgr_kdijkstraPath(
”SELECT gid as id, source, target, length as cost FROM ‘ || tbl ||”’,’
||v_startSource || ‘, ‘ ||’array[‘||v_endTarget||’] , false, false
) a, ‘
|| tbl || ‘ b
WHERE a.id3=b.gid
GROUP by id1
ORDER by id1’ into v_res_c ;
–从开始的终点到结束的终点最短路径
execute ‘SELECT st_linemerge(st_union(b.geom)) ‘ ||
‘FROM pgr_kdijkstraPath(
”SELECT gid as id, source, target, length as cost FROM ‘ || tbl ||”’,’
||v_startTarget || ‘, ‘ ||’array[‘||v_endTarget||’] , false, false
) a, ‘
|| tbl || ‘ b
WHERE a.id3=b.gid
GROUP by id1
ORDER by id1’ into v_res_d ;
if(ST_Length(v_res) > ST_Length(v_res_b)) then
v_res = v_res_b;
end if;
if(ST_Length(v_res) > ST_Length(v_res_c)) then
v_res = v_res_c;
end if;
if(ST_Length(v_res) > ST_Length(v_res_d)) then
v_res = v_res_d;
end if;
–如果找不到最短路径,就返回null
–if(v_res is null) then
— return null;
–end if;
–将v_res,v_startLine,v_endLine进行拼接
select st_linemerge(ST_Union(array[v_res,v_startLine,v_endLine])) into v_res;
select ST_Line_Locate_Point(v_res, v_statpoint) into v_perStart;
select ST_Line_Locate_Point(v_res, v_endpoint) into v_perEnd;
if(v_perStart > v_perEnd) then
tempnode = v_perStart;
v_perStart = v_perEnd;
v_perEnd = tempnode;
end if;
–截取v_res
SELECT ST_Line_SubString(v_res,v_perStart, v_perEnd) into v_shPath;
return v_shPath;
end;
$body$
LANGUAGE plpgsql VOLATILE STRICT;
四、数据发布
数据准备完成后,就需要用GeoServer来进行发布:
启动GeoServer,在浏览器中输入,http://localhost:8080/geoserver/web/,登录到GeoServer。
1.创建工作区
添加xblk名称的工作区。
2.添加数据存储:
填入对应的连接信息:
3.添加图层:
注意红框中的内容。
4.添加路径查询服务,添加图层,选择“配置新的SQL视图”:
视图名称:navigation
SQL语句:
SELECT * FROM pgr_fromAtoB(‘road_xblk’, %x1%, %y1%, %x2%, %y2%)
验证的正则表达式:^-?[\d.]+$
类型:LingString
SRID:4326
点击保存后,填入SRS,并自动计算范围:
五、结果展示
使用OpenLayer进行结果展示,代码请直接下载,结果如下:
调用方法:http://localhost:8098/geoserver/LocalhostTest/ows?service=WFS&version=1.0.0&request=GetFeature&typeName=LocalhostTest:roadway&maxFeatures=50&outputFormat=application%2Fjson&viewparams=x1:113.30498456954956;y1:23.141277489870415;x2:113.3072590827942;y2:23.13703522379429
说明:这个最短路径的算法有一定的问题,在特定的条件下,查找的不一定是最短的路径,需要对数据进行再处理,或者对算法进行优化。