[postgis-users] ST_Touches and line segment
mbdavis at refractions.net
Thu Mar 19 10:27:05 PDT 2009
And actually that should be
"AA:***-*1*-*** LL:1***-***-*** AL:***-1**-***"
In the SFS A represents 2D (Areal) features. P represents 0D (Point)
Martin Davis wrote:
> I've had some thoughts that it would be nice to extend the concept of
> Intersection Matrix Pattern to allow OR combinations of patterns.
> This seems to indicate that it's also necessary to be able to specify
> different patterns for different combinations of geometry dimension.
> Perhaps a syntax like:
> "PP:***-*1*-*** LL:1***-***-*** PL:***-1**-***"
> The LP pattern can be automatically inferred from this.
> Note that I'm also using a "dashed triplet" syntax, which is more
> readable than a solid string of 9 chars (think phone numbers or IP
> Kevin Neufeld wrote:
>> Martin Davis wrote:
>>> Kevin Neufeld wrote:
>>>> If you have overlapping polygons then use ST_Relate with a custom
>>>> matrix. IE. ST_Relate(g1, g2, '****1****') will return TRUE for
>>>> all geometry pairs where the intersection of the boundaries occur
>>>> on a line (1).
>>> You need to know the type of the input geometries. The above
>>> pattern will work for polygons, but not for lines. The L/L and P/L
>>> situation require different patterns:
>>> L/L: 1********
>>> P/L: ***1*****
>> Ah, yes, of course :)
>> The symmetric relation is also true:
>> L/P: *1*******
>> -- Kevin
>> postgis-users mailing list
>> postgis-users at postgis.refractions.net
Senior Technical Architect
Refractions Research, Inc.
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