[postgis-users] Bug in centroid() ?

[David TECHER]

As we say in French

"C'est vraiment chercher la petite bête :-)"




--- Pierrick Brihaye
<pierrick.brihaye at culture.gouv.fr> a écrit : > Hi,
> 
> Given the following data structure :
> 
> CREATE TABLE test_table(
>    gid serial NOT NULL,
>    the_geom public.geometry
> ) WITH OIDS;
> INSERT INTO test_table (the_geom)
>    VALUES (GeometryFromText('POINT(149149
> -2344411)',-1));
> 
> The following statement :
> 
> SELECT postgis_version(), envelope(the_geom),
> centroid(the_geom), 
> centroid(envelope(the_geom)) FROM test_table;
> 
> Returns (reformated as rows) :
> 
> "0.8 USE_GEOS=1 USE_PROJ=1 USE_STATS=1"
> "SRID=-1;POLYGON((149149 -2344411,149149
> -2344411,149149 -2344411,149149 
> -2344411,149149 -2344411))"
> "SRID=-1;POINT(149149 -2344411)"
> "SRID=-1;POINT(-1.#IND -1.#IND)"
> 
> First of all, could postgis_version() be more
> verbose and, for example, 
> display the GEOS and the PROJ version ? It would
> help in debugging, 
> wouldn't it ?
> 
> Second, my PostGIS version is old and maybe my
> problem is already fixed. 
> Is so, please forgive me. I didn't see anything
> about this topic in the 
> PostGIS and GEOS CVS logs though...
> 
> As you can see, the centroid(envelope(the_geom))
> can't return a valid 
> result. OK, I admit that this indirection is quite
> odd, but is should 
> return that same result as centroid(the_geom),
> shouldn't it ?
> 
> Whose fault is it ? GEOS's or PostGIS's ?
> 
> Cheers,
> 
> -- 
> Pierrick Brihaye, informaticien
> Service régional de l'Inventaire
> DRAC Bretagne
> mailto:pierrick.brihaye at culture.gouv.fr
> +33 (0)2 99 29 67 78
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