Hi Paul. I had the same problem as you. I had SOME geometries of my
database as MultiLineString (Imported from ESRI).
First sorry about my poor english.
I dont know if this message should go here or in pgrouting list.
I'm going to try to explain what are the things you have to do to get
the complete route, splited in the nearest points of start and end.
1) You have to get the nearest segment of your points.
2) Use source and target of that segments to get the route.
3) Now you have to get the first segment, but starting in the nearest
point of your start point. But be careful here. Yo have to see the
direction of the segment. You can do that comparing the source and
target of the the segment 1 and 2. Here You will know when to use:
Select ST_LINE_SUBSTRING(
ST_LineMerge(line),
0,
ST_line_locate_point(st_linemerge(line),<startPoint>)) from route;
Or
Select ST_LINE_SUBSTRING(
ST_LineMerge(line),
ST_line_locate_point(st_linemerge(line),<startPoint>),
1) from route;
4) Now get all the other segments.
5) Detect the LAST segment (This is going to be the same segment that
you get nearest your point). And compare this segment with the segment
before this one. Here you have to do the same you do with the first segment.
Remember that st_line_locate_point return a number between 0-1 that
represent nearest position IN the line of the startPoint.
If you want you could send an email to pgrouting mailing list and maybe
there we can do some Store Procedure to get what you want.
Hope this helps.
Regards
Emiliano Romero
paweluz wrote:
Hi everybody!
First sorry for my poor English. My name is Paul. I have some problem with
the routing. I was doing tutorial form page
http://pgrouting.postlbs.org/wiki/WorkshopFOSS4G2007
http://pgrouting.postlbs.org/wiki/WorkshopFOSS4G2007
I got pretty good. The results can be see at page:
http://img509.imageshack.us/img509/9250/routing.jpg
http://img509.imageshack.us/img509/9250/routing.jpg
I you can see, it does work but not to the end. I have to segment the start
end ending geometry.
Get the right start and end point. I read a lot about this in the Internet.
I found some
informations. I know that I have to use this 2 functions
line_locate_point();
line_substring();
Then I read more, and I found that I actually cant use them because I don't
have coreect geometry.
I should have linestring but I have multilinestring - as you can see on the
screen
http://img22.imageshack.us/img22/2484/dbase900913.jpg
http://img22.imageshack.us/img22/2484/dbase900913.jpg
So I started to look for other function and I found out about function
'line_interpolate_point'. I
try to use it but all I got were empty rows. I used like this.
SELECT line_interpolate_point(GeometryN(the_geom,900913),
line_locate_point(GeometryN(the_geom,900913),PointFromText('POINT(1725140.73233
6788749.88889)')))
FROM zielona_gora_routing
But it gives me only empty rows :( SO I don't know what to do now. I am so
close to the answer but
I don't know how to get it right. Can anybody please help me. I thinking
that I have to update
this function
$start = split(' ',$_REQUEST["startpoint"]);
$startPoint = array($start[0], $start[1]);
// Retrieve end point
$end = split(' ',$_REQUEST["finalpoint"]);
$endPoint = array($end[0], $end[1]);
$startEdge = findNearestEdge($startPoint);
$endEdge = findNearestEdge($endPoint);
//FUNCTION!!!!!!
unction findNearestEdge($lonlat) {
// Connect to database
$con = pg_connect("dbname=".PG_DB." host=".PG_HOST." user=".PG_USER);
$lonlat1=$lonlat[0]-200;
$lonlat2=$lonlat[1]-200;
$lonlat3=$lonlat[0]+200;
$lonlat4=$lonlat[1]+200;
$sql = "SELECT gid, source, target, the_geom,
distance(the_geom, GeometryFromText(
'POINT(".$lonlat[0]." ".$lonlat[1].")', 900913)) AS dist
FROM ".TABLE."
WHERE the_geom && setsrid(
'BOX3D(".$lonlat1."
".$lonlat2.",
".$lonlat3."
".$lonlat4.")'::box3d, 900913)
ORDER BY dist LIMIT 1";
$query = pg_query($con,$sql);
$edge['gid'] = pg_fetch_result($query, 0, 0);
$edge['source'] = pg_fetch_result($query, 0, 1);
$edge['target'] = pg_fetch_result($query, 0, 2);
$edge['the_geom'] = pg_fetch_result($query, 0, 3);
// Close database connection
pg_close($con);
return $edge;
}
You can see this function in the tutorial that link I gave at the top of
this post. Can anybody please help me. I would really appreciate...
Regards
Paul
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