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Corrected and augmented the new chapter about ensuring OGC compliancy.

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git-svn-id: http://svn.osgeo.org/postgis/trunk@1604 b70326c6-7e19-0410-871a-916f4a2858ee
This commit is contained in:
Sandro Santilli 2005-04-07 19:00:32 +00:00
parent f6895129b7
commit ea5074d802
1 changed files with 16 additions and 6 deletions
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22
doc/postgis.xml
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@ -1212,9 +1212,11 @@ SELECT AddGeometryColumn( 'roads', 'roads_geom', -1, 'GEOMETRY', 3 );</programli
<sect2>
<title>Ensuring OpenGIS compliancy of geometries</title>
<para>Most of the PostGIS functions rely on the assumption that your geometry data conforms
to the OpenGIS Simple Feature Specification. To check whether your geometries are valid
in this sense, you can use the isvalid() function:</para>
<para>Most of the functions implemented by the GEOS library
rely on the assumption that your geometries are valid
as specified by the OpenGIS Simple Feature Specification.
To check validity of geometries you can use the
<link linkend="IsValid">isvalid()</link> function:</para>
<programlisting>gisdb=# select isvalid('LINESTRING(0 0, 1 1)'), isvalid('LINESTRING(0 0,0 0)');
isvalid | isvalid
@ -1235,8 +1237,16 @@ SELECT AddGeometryColumn( 'roads', 'roads_geom', -1, 'GEOMETRY', 3 );</programli
uses, and you should contact the PostGIS developers. The same is true if an PostGIS returns
an invalid geometry for valid input.</para>
<programlisting>CREATE TABLE roads ( ROAD_ID int4, ROAD_NAME varchar(128) );
SELECT AddGeometryColumn( 'roads', 'roads_geom', -1, 'GEOMETRY', 3 );</programlisting>
<note>
<para>
Strictly compliant OGC geometries cannot have Z or M values.
The <link linkend="IsValid">IsValid()</link> function won't
consider higher dimensioned geometries invalid ! Invocations
of AddGeometryColumn() will add a constraint checking geometry
dimensions, so it is enough to specify 2 there.
</para>
</note>
</sect2>
</sect1>
@ -4516,7 +4526,7 @@ FROM geometry_table;</literallayout>
</listitem>
</varlistentry>
<varlistentry>
<varlistentry id="IsValid">
<term>isvalid(geometry)</term>
<listitem>