[postgis-devel] isvalid() error

[Carl Anderson]

strk at refractions.net wrote:

>PostGIS always allowed polygon rings with 3 points.
>In this case it disagrees with GEOS about this.
>Also, PostGIS does not allow 0 points.
>
>Should we enforce GEOS constraints or just have isvalid
>return FALSE in these cases ?
>
>  
>
a LINESTRING with 3 points is not simple (passes though the same point 
in space twice) and cannot be a LINEARRING. Hence it cannot be part of a 
valid POLYOGN

C.

>--strk;
>
>On Thu, Jan 13, 2005 at 05:07:59PM -0500, Carl Anderson wrote:
>  
>
>>need to test for ring counts prior to sending to GEOS
>>
>>select  isvalid(geometry('POLYGON((0 0,0 1,0 0))'));
>>NOTICE:   IllegalArgumentException: Number of points must be 0 or >3
>>ERROR:      POSTGIS2GEOS conversion failed
>>
>>
>>-- 
>>Carl Anderson
>>GIS Manager Fulton County, Georgia
>>carl.anderson at co.fulton.ga.us
>>404.730.8026
>>
>>
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>
>  
>


-- 
Carl Anderson
GIS Manager Fulton County, Georgia
carl.anderson at co.fulton.ga.us
404.730.8026


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