[postgis-users] Re: intersects(), touches(), overlaps() documentation issue

[Amit Kulkarni]

Hi Michael and Martin,

I have uploaded the .shp here, and have stripped it of any identifying
columns (I had to), but have included the .prj file just in case...

http://puggy.symonds.net/~amit/chk_direction.tar

intersects(a,b) returns true

I don't know how to do a relate (a,b) to get the intersection matrix
for now, am rushed for time for now. Would you send me the actual SQL
query if possible? I can do it in next 30 mins or next week. I won't
have reliable access to a computer for about a week, will follow up
when I get back.

We have decided to clean up geometry completely in a desktop GIS before
reinserting it back to PostGIS. I saw some threads on inserting
valid/invalid geometries which strk said he needed help on. Does
anybody know what happened to that effort?

Thanks in advance for your help guys!

--- Amit Kulkarni <amitkulz at yahoo.com> wrote:

> All,
> 
> I had a situation where a line overlapped another line for a very
> small
> distance near its endpoints. touches() returned true but I was
> confused
> why my stored proc was not executing as it should. After some
> frustrated hours checking inside the loop, I thought to pull up the
> offending segments in a Desktop GIS and lo! I saw the overlap
> immediately.
> 
> I was under the impression that touches() returns true and only true
> if
> endpoints touched. Is that impression invalid? intersects() returns
> true but overlap() doesn't return true?
> 
> I am attaching a jpeg. If needed I can attach a .shp
> 
> Thanks for your input
> 
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