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<TITLE>RE: [postgis-devel] isvalid(geom), but st_ashexewkb(geom,'NDR')::geometry fails</TITLE>
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<P><FONT SIZE=2>David,<BR>
<BR>
I don't think that is valid WKT syntax for an EMPTY multipolygon. If I try to stuff that in via ST_GeomFromText it returns invalid geometry. Not sure how you got that in there.<BR>
<BR>
It should be<BR>
<BR>
SELECT ST_GeomFromText('MULTIPOLYGON EMPTY');<BR>
<BR>
<BR>
On 1.3.3 and 1.3.4SVN - when I do this - I get the below which is also kind of odd. I would have expected it to maintain the empty polygon.<BR>
<BR>
SELECT ST_IsValid(the_geom), ST_AsText(the_geom), ST_IsEmpty(the_geom), ST_AsEWKT(the_geom) FROM (SELECT ST_GeomFromText('MULTIPOLYGON EMPTY') As the_geom) As foo ;<BR>
st_isvalid | st_astext | st_isempty | st_asewkt <BR>
------------+--------------------------+------------+--------------------------<BR>
t | GEOMETRYCOLLECTION EMPTY | t | GEOMETRYCOLLECTION EMPTY<BR>
(1 row)<BR>
<BR>
Hope that helps,<BR>
Regina<BR>
-----Original Message-----<BR>
From: postgis-devel-bounces@postgis.refractions.net on behalf of David Fuhry<BR>
Sent: Thu 10/23/2008 11:28 PM<BR>
To: PostGIS Development Discussion<BR>
Subject: [postgis-devel] isvalid(geom), but st_ashexewkb(geom,'NDR')::geometry fails<BR>
<BR>
I have an empty multipolygon which isvalid(), but which the parser<BR>
throws "ERROR: geometry requires more points" on. Is this a bug in<BR>
isvalid(), or in the parser? Interestingly, st_isempty() returns false.<BR>
<BR>
db=> select geom from tt;<BR>
geom<BR>
------------------------------------------------------<BR>
0106000020C90E00000100000001030000000100000000000000<BR>
(1 row)<BR>
<BR>
db=> select st_astext(geom) from tt;<BR>
st_astext<BR>
------------------------<BR>
MULTIPOLYGON(( EMPTY))<BR>
(1 row)<BR>
<BR>
db=> select isvalid(geom) from tt;<BR>
isvalid<BR>
---------<BR>
t<BR>
(1 row)<BR>
<BR>
db=> select st_ashexewkb(geom,'NDR')::geometry from tt;<BR>
ERROR: geometry requires more points<BR>
<BR>
db=> select st_isempty(geom) from tt;<BR>
st_isempty<BR>
------------<BR>
f<BR>
(1 row)<BR>
<BR>
db=> select version(), postgis_version();<BR>
version<BR>
| postgis_version<BR>
-----------------------------------------------------------------------<BR>
-----------------+---------------------------------------<BR>
PostgreSQL 8.3.1 on i486-pc-linux-gnu, compiled by GCC cc (GCC) 4.2.3<BR>
(Debian 4.2.3-4) | 1.3 USE_GEOS=1 USE_PROJ=1 USE_STATS=1<BR>
(1 row)<BR>
<BR>
Thanks,<BR>
<BR>
Dave<BR>
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<BR>
</FONT>
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