Hello, Anyone has any ideas/tips of how to break lines at intersections ? I have a a layer of lines and I want to break them at intersections with them selfs, also (not that important but would be nice) break lines forming a collapsed loop, for example 0.0;1.0;0.0 is broken at 1.0.
Currently this can be done in grass with v.clean tool=break,rmdupl but it's relatively hard to add GRASS to a web app. So far I came up with this query and out of ideas right now: SELECT DISTINCT gid, ST_AsText(intersect_geom), ST_Line_Locate_Point(GeometryN(the_geom, 1), intersect_geom) as point_loc1 FROM (SELECT a.gid, ST_Intersection(a.the_geom, b.the_geom) AS intersect_geom, a.the_geom FROM roads as a, roads as b WHERE ST_Intersects(a.the_geom, b.the_geom) AND (a.gid = 1) ) AS res1 WHERE GeometryType(intersect_geom) = 'POINT' -- Need support for MULTILINESTRINGS, take start and end point ? ORDER BY point_loc1 which has the following result: http://jsfiddle.net/9RJ8a/ I have the line, and the point positions on the line, but I can't get around how to create my NEW broken lines with ST_Line_Substring(geometry a_linestring, float startfraction, float endfraction) Any suggestion of how to accomplished this ? is the approach correct ? any other ideas ? _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
