[postgis-users] split line at polygon edge
hugues.francois at irstea.fr
Thu Mar 17 00:15:48 PDT 2016
Dis you take a look at the query result ? I think you should first try to
see what is the type of geometry returned using ST_GeometryType(). You may
have some geometrycollections and I’m not sure QGis can handle it. In this
case you could extract lines using ST_CollectionExtract().
To achieve what you want to do, you’ll be able to compare your original
lines table with the result of your query using ST_Difference().
De : postgis-users [mailto:postgis-users-bounces at lists.osgeo.org] De la part
de Garret W
Envoyé : jeudi 17 mars 2016 04:11
À : postgis-users at lists.osgeo.org
Objet : [postgis-users] split line at polygon edge
Hi Ive been looking for a way to take several hundred lines and split them
where they intersect a polygon while also giving them the ID of the polygon
they fall in. Ive seen many posts on splitting polygons. But its been
difficult for me to adapt those examples.
Ive been able to get an output from this:
select st_intersection(t.geom, d.geom),t.trails_id, d.id from
public.temp_trails as t, public.polys as d;
Its giving me the line and IDs that I wanted but the geom is unreadable for
some reason by QGIS.
99.9% of the lines fall within a polygon. Id like to still hang on to those
few lines that arent contained in a polygon. They should just be split with
no ID added
Im using; postgis 2.2, postgresql 9.5
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