Document ST_MinimumBoundingCircle

git-svn-id: http://svn.osgeo.org/postgis/trunk@3631 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/doc/reference_new.xml b/doc/reference_new.xml
index c9018119bf32f2a5ad0b9fcbff4ab51cdb5aaa92..19d8f9ad6d9f219cff7662e25c5f22d7a509e769 100644 (file)
--- a/doc/reference_new.xml
+++ b/doc/reference_new.xml
@@ -12018,6 +12018,78 @@ SELECT ST_AsEWKT(ST_LineToCurve(ST_GeomFromEWKT('LINESTRING(1 2 3, 3 4 8, 5 6 4,
                <para><xref linkend="ST_Union" /></para>
          </refsection>
        </refentry>
+       
+       <refentry id="ST_MinimumBoundingCircle">
+         <refnamediv>
+               <refname>ST_MinimumBoundingCircle</refname>
+               <refpurpose>Returns the smallest circle polygon that can fully contain a geometry.  
+                       Defaults to 48 segs per quarter to approximate a circle</refpurpose>
+         </refnamediv>
+
+         <refsynopsisdiv>
+               <funcsynopsis>
+                 <funcprototype>
+                       <funcdef>geometry<function>ST_MinimumBoundingCircle</function></funcdef>
+                       <paramdef><type>geometry </type> <parameter>geomA</parameter></paramdef>
+                 </funcprototype>
+                 <funcprototype>
+                       <funcdef>geometry<function>ST_MinimumBoundingCircle</function></funcdef>
+                       <paramdef><type>geometry </type> <parameter>geomA</parameter></paramdef>
+                       <paramdef><type>integer </type> <parameter>num_segs_per_qt_circ</parameter></paramdef>
+                 </funcprototype>
+               </funcsynopsis>
+         </refsynopsisdiv>
+
+         <refsection>
+               <title>Description</title>
+                       <para>Returns the smallest circle polygon that can fully contain a geometry.  
+                       Defaults to 48 segs per quarter to approximate a circle</para>
+
+                       <para>It is often used with MULTI and Geometry Collections.
+               Although it is not an aggregate - you can use it in conjunction
+               with ST_Collect to get the minimum bounding cirlce of a set of geometries.
+               ST_MinimumBoundingCircle(ST_Collect(somepointfield)).</para>
+
+               <para>It is often referred to as the  Roeck test.</para>
+
+               <para>Requires GEOS module</para>
+
+
+         </refsection>
+
+         <refsection>
+               <title>Examples</title>
+<programlisting>SELECT d.disease_type,
+       ST_MinimumBoundingCircle(ST_Collect(d.the_geom)) As the_geom
+       FROM disease_obs As d
+       GROUP BY d.disease_type;
+
+       --Only use 8 segs to approximate a quarter circle
+       SELECT ST_AsText(ST_MinimumBoundingCircle(
+               ST_Collect(
+                       ST_GeomFromEWKT('LINESTRING(1 2,3 4)'),
+                               ST_MakePoint(0, 2)), 8
+                               )) As wktmbc;
+wktmbc
+-----------
+POLYGON((3.30277563773199 3,3.26813580935709 2.64829592031203,3.16554751341057 2.31010763116856,
+2.9989531605735 1.99843151886317,2.7747548783982 1.7252451216018,2.50156848113683 1.50104683942651,
+2.18989236883145 1.33445248658943,1.85170407968797 1.23186419064291,1.5 1.19722436226801,
+1.14829592031204 1.23186419064291,0.81010763116856 1.33445248658943,0.498431518863177 1.5010468394265,
+0.225245121601807 1.7252451216018,0.00104683942650734 1.99843151886317,-0.16554751341057 2.31010763116855,
+-0.268135809357086 2.64829592031203,-0.302775637731995 2.99999999999999,-0.268135809357088 3.35170407968796,
+-0.165547513410575 3.68989236883144,0.00104683942650074 4.00156848113682,0.225245121601799 4.27475487839819,
+0.498431518863167 4.49895316057349,0.81010763116855 4.66554751341057,1.14829592031203 4.76813580935709,
+1.49999999999999 4.80277563773199,1.85170407968796 4.76813580935709,2.18989236883144 4.66554751341057,
+2.50156848113682 4.4989531605735,2.77475487839819 4.2747548783982,2.99895316057349 4.00156848113683,
+3.16554751341057 3.68989236883145,3.26813580935709 3.35170407968797,3.30277563773199 3))
+                               </programlisting>
+         </refsection>
+         <refsection>
+               <title>See Also</title>
+               <para><xref linkend="ST_Collect" />, <xref linkend="ST_ConvexHull" /></para>
+         </refsection>
+       </refentry>
 
        <refentry id="ST_Polygonize">
                <refnamediv>