Hi,
According to SQL/MM and in PostGIS the intersection of two linestrings
can be:
a Empty ST_Point (GeometryCollection Empty in PostGIS 1.5)
a ST_Point
a ST_LineString
a ST_MultiPoint
a ST_MultiLineString
a ST_GeomCollection with ST_Point and ST_LineString.
Cheers,
Jose
On 19/03/2012 20:25, [email protected] wrote:
Whenever the intersection of two lines is a linestring.
eg:
select astext(ST_intersection(ST_makeline(ST_Makepoint(0,0),
ST_Makepoint(1,1)),ST_Makeline(ST_Makepoint(0.5, 0.5),
ST_Makepoint(1.5,1.5))));
astext
-------------------------
LINESTRING(0.5 0.5,1 1)
(1 row)
Brent
--- On *Tue, 3/20/12, Bob Pawley /<[email protected]>/* wrote:
From: Bob Pawley <[email protected]>
Subject: [postgis-users] St_intersection
To: [email protected]
Date: Tuesday, March 20, 2012, 6:44 AM
Hi
I am querying a geometry looking for intersection point between a
line and an other geometry.
The return is 2 points and 2 linestrings. (when I use st_union a
geometry collection results)
Can anyone tell me under what conditions that a st_intersection
would return a linestring??
insert into num_search (the_geom3)
select st_intersection(Num_Search.the_geom1, entities.wkb_geometry)
from entities, Num_Search
where Num_Search.seq = 'R'
and st_intersects(entities.wkb_geometry, Num_Search.the_geom1) = True
Bob
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