[postgis-devel] Issue 148 in postgis: st_touches doesn't work as it should on st_touches(line,point)

codesite-noreply at google.com codesite-noreply at google.com
Wed Apr 8 08:37:38 PDT 2009


Updates:
	Status: Invalid

Comment #1 on issue 148 by robe.... at cityofboston.gov: st_touches doesn't  
work as it should on st_touches(line,point)
http://code.google.com/p/postgis/issues/detail?id=148

Nicklas -- I think this is by design.  Touches is a weird thing -- but in  
the docs it
says

2 geometries only touch if their boundaries share points together.  The  
boundary of a
line string is a MULTIPOINT.  If you do this

SELECt ST_AsText(ST_Boundary('LINESTRING(0 0, 1 1, 0 2)'::geometry))

you get this -- MULTIPOINT(0 0,0 2)  -- so the only geometries that qualify  
as
touching this linestring are 0 0  and 0 2 as you have observed.

Kevin please correct me if I am wrong because this is a very touchy subject  
(well in
terms of nuances anyway)

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