[postgis-users] ST_Touches and line segment

[Martin Davis]

And actually that should be

"AA:***-*1*-*** LL:1***-***-*** AL:***-1**-***"

In the SFS A represents 2D (Areal) features.  P represents 0D (Point) 
features.


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 
> addresses)
>
>
> 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
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>>
>

-- 
Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022