[postgis-users] NOTICE: IllegalArgumentException: point array must contain 0 or >1 elements, ERROR: Exception in LWGEOM2GEOS

[Martin Davis]

This error is due to a design choice in JTS/GEOS, which reflected the 
OGC SFS spec - LineStrings are not allowed to have a single point.

For users who use JTS and GEOS directly, this isn't as much of an issue, 
because their language environments allow them to catch exceptions 
easily.  But in PostGIS it might be better to trap this condition in the 
isvalid code and return an appropriate result (false).

Daniel Degasperi wrote:
> |*Hi,
> I have some problems with a MultiLinestring imported with *||*shp2pgsql.
>
> If I try to check it's validity (or try to do anything else on it)*||*:
>
> SELECT 
> isvalid('0105000020E0670000010000000102000020E06700000100000016DA52BA62A04141FFF3AD290B735241');
>
> *||*I get the Exception in my e-mail subject.
>
> How can I check the geometry, if already isvalid chokes. I could only 
> select NumPoints(the_geom) and compare it to the allowed range of the 
> geometry type (e.g. 0 or > 1 for MULTILINESTRINGS).
>
> Can this be considered to be a bug of PostGIS/GEOS?
>
> Software stack:
> CentOS 5.4, 64 bit
> PostgreSQL 8.2.14 (from CentOS Testing)
> PostGIS 1.4.1
> GEOS: 3.1.1
>
> *||*Best regards
> Daniel
>
> *|
> -- 
>   Daniel Degasperi
>   Software Developer
>   daniel.degasperi at r3-gis.com
>   
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-- 
Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022