Documentation tweaks for st_voronoi from Anne Blankert

git-svn-id: http://svn.osgeo.org/postgis/trunk@16093 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/doc/reference_processing.xml b/doc/reference_processing.xml
index 4216c12f54d5b1e9b9c00c8130ee2508d728d603..f1ad7700157d8d2a9f0d89094c0417b7e566aaca 100644 (file)
--- a/doc/reference_processing.xml
+++ b/doc/reference_processing.xml
@@ -3709,24 +3709,22 @@ MULTILINESTRING((3 4,4 5),(1 2,3 4))
 
          <refsection>
                <title>Description</title>
-
                <para>
                        ST_VoronoiLines computes a two-dimensional <ulink url="https://en.wikipedia.org/wiki/Voronoi_diagram">Voronoi diagram</ulink> from the vertices of
-            the supplied geometry and returns the boundaries between cells in that diagram as a MultiLineString.
-        </para>
-
+                       the supplied geometry and returns the boundaries between cells in that diagram as a MultiLineString.
+                       Returns null if input geometry is null. Returns an empty geometry collection if the input geometry contains only one vertex. Returns an empty geometry collection if the extend_to envelope has zero area.
+               </para>
                <para>
                        Optional parameters:
-               <itemizedlist>
-                       <listitem>
-                <para> 'tolerance' : The distance within which vertices will be considered equivalent.  Robustness of the algorithm can be improved by supplying a nonzero tolerance distance.  (default = 0.0)</para>
-                       </listitem>
-                       <listitem>
-                               <para>'extend_to' : If a geometry is supplied as the "extend_to" parameter, the diagram will be extended to cover the
-                                       envelope of the "extend_to" geometry, unless that envelope is smaller than the default envelope.
-                                       (default = NULL)</para>
-                       </listitem>
-               </itemizedlist>
+                       <itemizedlist>
+                               <listitem>
+                                       <para> 'tolerance' : The distance within which vertices will be considered equivalent.  Robustness of the algorithm can be improved by supplying a nonzero tolerance distance.  (default = 0.0)</para>
+                               </listitem>
+                               <listitem>
+                                       <para>'extend_to' : If a geometry is supplied as the "extend_to" parameter, the diagram will be extended to cover the envelope of the "extend_to" geometry, unless
+                                               that envelope is smaller than the default envelope (default = NULL, default envelope is boundingbox of input geometry extended by about 50% in each direction).</para>
+                               </listitem>
+                       </itemizedlist>
                </para>
 
                <para>Availability: 2.3.0 - requires GEOS &gt;= 3.5.0.</para>
@@ -3806,20 +3804,21 @@ MULTILINESTRING((135.555555555556 270,36.8181818181818 92.2727272727273),(36.818
                <para>
                        ST_VoronoiPolygons computes a two-dimensional <ulink url="https://en.wikipedia.org/wiki/Voronoi_diagram">Voronoi diagram</ulink> from the vertices of
                        the supplied geometry.  The result is a GeometryCollection of Polygons that covers an envelope larger than the extent of the input vertices.
+                       Returns null if input geometry is null. Returns an empty geometry collection if the input geometry contains only one vertex. Returns an empty geometry collection if the extend_to envelope has zero area.
                </para>
 
                <para>
                        Optional parameters:
-               <itemizedlist>
-                       <listitem>
-                       <para>'tolerance' : The distance within which vertices will be considered equivalent.  Robustness of the algorithm can be improved by supplying a nonzero tolerance distance.  (default = 0.0)</para>
-                       </listitem>
-                       <listitem>
-                               <para>'extend_to' : If a geometry is supplied as the "extend_to" parameter, the diagram will be extended to cover the
-                                       envelope of the "extend_to" geometry, unless that envelope is smaller than the default envelope.
-                                       (default = NULL)</para>
-                       </listitem>
-               </itemizedlist>
+                       <itemizedlist>
+                               <listitem>
+                                       <para> 'tolerance' : The distance within which vertices will be considered equivalent.  Robustness of the algorithm can be improved by supplying a nonzero tolerance distance.  (default = 0.0)</para>
+                               </listitem>
+                               <listitem>
+                                       <para>'extend_to' : If a geometry is supplied as the "extend_to" parameter, the diagram will be extended to cover the envelope of the "extend_to" geometry, unless
+                                               that envelope is smaller than the default envelope (default = NULL, default envelope is boundingbox of input geometry extended by about 50% in each direction).
+                                       </para>
+                               </listitem>
+                       </itemizedlist>
                </para>
 
                <para>Availability: 2.3.0 - requires GEOS &gt;= 3.5.0.</para>