preliminary documentation for raster version of ST_Union aggregate function

git-svn-id: http://svn.osgeo.org/postgis/trunk@8352 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/doc/reference_raster.xml b/doc/reference_raster.xml
index 884b41d223cb26d96f52b10fee56e9c1e9fd7bbf..b03d79f25acbdfe30a327aa9edd5ff9ca19b9092 100644 (file)
--- a/doc/reference_raster.xml
+++ b/doc/reference_raster.xml
@@ -6545,6 +6545,65 @@ UPDATE wind
                                <para><xref linkend="RT_ST_AddBand" />,<xref linkend="RT_ST_Band" />, <xref linkend="RT_ST_BandPixelType" />,<xref linkend="RT_ST_MakeEmptyRaster" />,  <xref linkend="reclassarg" />, <xref linkend="RT_ST_Value" /></para>
                        </refsection>
                </refentry>
+               
+               <refentry id="RT_ST_Union">
+                       <refnamediv>
+                               <refname>ST_Union</refname>
+                               <refpurpose>Returns the union of a set of raster tiles into a single raster composed of 1 band.  If no band is specified for unioning, band num 1 is assumed.  The resulting raster's extent is the extent of the whole set.  In the case of intersection, the resulting value is defined by p_expression which is one of the following: LAST - the default when none is specified, MEAN, SUM, FIRST </refpurpose>
+                       </refnamediv>
+               
+                       <refsynopsisdiv>
+                               <funcsynopsis>
+                                 <funcprototype>
+                                       <funcdef>raster <function>ST_Union</function></funcdef>
+                                       <paramdef><type>setof raster </type> <parameter>rast</parameter></paramdef>
+                                 </funcprototype>
+                               </funcsynopsis>
+                               <funcsynopsis>
+                                 <funcprototype>
+                                       <funcdef>geometry <function>ST_Union</function></funcdef>
+                                       <paramdef><type>raster set</type> <parameter>rast</parameter></paramdef>
+                                               <paramdef><type>integer</type> <parameter>band_num</parameter></paramdef>
+                                 </funcprototype>
+                               </funcsynopsis>
+                               <funcsynopsis>
+                                 <funcprototype>
+                                       <funcdef>geometry <function>ST_Union</function></funcdef>
+                                       <paramdef><type>raster set</type> <parameter>rast</parameter></paramdef>
+                                       <paramdef><type>text</type> <parameter>p_expression</parameter></paramdef>
+                                 </funcprototype>
+                               </funcsynopsis>
+                               <funcsynopsis>
+                                 <funcprototype>
+                                       <funcdef>geometry <function>ST_Union</function></funcdef>
+                                       <paramdef><type>raster set</type> <parameter>rast</parameter></paramdef>
+                                       <paramdef><type>text</type> <parameter>p_expression</parameter></paramdef>
+                                       <paramdef><type>integer</type> <parameter>band_num</parameter></paramdef>
+                                 </funcprototype>
+                               </funcsynopsis>
+                       </refsynopsisdiv>
+               
+                       <refsection>
+                               <title>Description</title>
+                               
+                               <para>Returns the union of a set of raster tiles into a single raster composed of 1 band.  If no band is specified for unioning, band num 1 is assumed.  The resulting raster's extent is the extent of the whole set.  In the case of intersection, the resulting value is defined by p_expression which is one of the following: LAST - the default when none is specified, MEAN, SUM, FIRST </para>
+                               
+                               <note><para>There are several other variants of this function not installed by default in PostGIS 2.0.0 -- these can be found in the raster/scripts/plpgsql/st_union.sql file of postgis source code.</para>
+                               </note>
+                               <para>Availability: 2.0.0 </para>
+                       </refsection>
+                               
+                       <refsection>
+                               <title>Examples</title>
+                               <!-- coming soon -->
+                       </refsection>
+               
+                       <!-- Optionally add a "See Also" section -->
+                       <refsection>
+                               <title>See Also</title>
+                               <para><xref linkend="RT_ST_Envelope" />, <xref linkend="RT_ST_ConvexHull" /></para>
+                       </refsection>
+               </refentry>
        </sect1>
        
        <sect1 id="RT_Operators">