Addition of notes differentiating ST_DumpPolygons and

ST_PixelsAsPolygons

git-svn-id: http://svn.osgeo.org/postgis/trunk@10026 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/doc/reference_raster.xml b/doc/reference_raster.xml
index 1d6ad7990e3aef1012483ae4b004e6561b4bc9c1..2df1517aa1d3b8aeab966f589cf1d5287970c71b 100644 (file)
--- a/doc/reference_raster.xml
+++ b/doc/reference_raster.xml
@@ -3049,6 +3049,12 @@ WHERE rid=2;
                                
                                <para>Returns the geometry that bounds every pixel of a raster band along with the value (double precision), the X and the Y raster coordinates (integers) of each pixel.</para>
 
+                               <note>
+                                       <para>
+                                               ST_PixelAsPolygons returns one geometry for every pixel.  This is different than ST_DumpAsPolygons where each geometry represents one or more pixels with the same pixel value.
+                                       </para>
+                               </note>
+
                        </refsection>
                                
                        <refsection>
@@ -6244,6 +6250,11 @@ FROM (SELECT ST_SetRotation(rast, 0.1, 0.1) As rast
                                <para>Availability: Requires GDAL 1.7 or higher.</para>
                                <note><para>If there is a no data value set for a band, pixels with that value will not be returned.</para></note>
                                <note><para>If you only care about count of pixels with a given value in a raster, it is faster to use <xref linkend="RT_ST_ValueCount" />.</para></note>
+                               <note>
+                                       <para>
+                                               This is different than ST_PixelAsPolygons where one geometry is returned for each pixel regardless of pixel value.
+                                       </para>
+                               </note>
                  </refsection>
        
                  <refsection>