#657: correct the documentation on ST_Project to reflect it expects bearing measured...

git-svn-id: http://svn.osgeo.org/postgis/trunk@11026 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/doc/reference_measure.xml b/doc/reference_measure.xml
index 2bea450092147d7b81dd5c17ec4b61b2cc284d9f..4458cff1646cf96d9365e0d184859f03498aa4a2 100644 (file)
--- a/doc/reference_measure.xml
+++ b/doc/reference_measure.xml
@@ -3607,11 +3607,11 @@ SELECT ST_AsEWKT(ST_PointOnSurface(ST_GeomFromEWKT('LINESTRING(0 5 1, 0 0 1, 0 1
          </refsection>
        </refentry>
 
-               <refentry id="ST_Project">
+       <refentry id="ST_Project">
                  <refnamediv>
                        <refname>ST_Project</refname>
 
-                       <refpurpose>Returns a <varname>POINT</varname> projected from a start point using a bearing and distance.</refpurpose>
+                       <refpurpose>Returns a <varname>POINT</varname> projected from a start point using a distance and bearing (azimuth) in radians.</refpurpose>
                  </refnamediv>
 
                  <refsynopsisdiv>
@@ -3632,21 +3632,32 @@ SELECT ST_AsEWKT(ST_PointOnSurface(ST_GeomFromEWKT('LINESTRING(0 5 1, 0 0 1, 0 1
                  <refsection>
                        <title>Description</title>
 
-                       <para>Returns a <varname>POINT</varname> projected from a start point using an azimuth (bearing) and distance.</para>
+                       <para>Returns a <varname>POINT</varname> projected from a start point using an azimuth (bearing) measured in radians and distance measured in meters.</para>
                        <para>Distance, azimuth and projection are all aspects of the same operation, describing (or in the case of projection, constructing) the relationship between two points on the world.</para>
-                       <para>The azimuth is sometimes called the heading or the bearing in navigation. It is measured relative to true north (azimuth zero). East is azimuth 90, south is azimuth 180, west is azimuth 270.</para>
+                       <para>The azimuth is sometimes called the heading or the bearing in navigation. It is measured relative to true north (azimuth zero). East is azimuth 90 (<varname>pi/2</varname>), south is azimuth 180 (<varname>pi</varname>), west is azimuth 270 (<varname>pi*1.5</varname>).</para>
                        <para>The distance is given in meters.</para>
 
                  </refsection>
 
                  <refsection>
-                       <title>Examples</title>
+                       <title>Example: Using degrees - projected point 100,000 meters and bearing 45 degreees </title>
 
-                       <programlisting>SELECT ST_AsText(ST_Project('POINT(0 0)'::geography, 100000, 45));
-                  st_astext
-       ------------------------------------------
-        POINT(0.63523102912532 0.63947233472882)
-       (1 row)
+                       <programlisting>SELECT ST_AsText(ST_Project('POINT(0 0)'::geography, 100000, radians(45.0)));
+                         st_astext
+------------------------------------------
+ POINT(0.63523102912532 0.63947233472882)
+(1 row)
+       </programlisting>
+                 </refsection>
+                 
+                 <refsection>
+                       <title>Example: Using radians - projected point 100,000 meters and bearing pi/4 (45 degreees) </title>
+
+                       <programlisting>SELECT ST_AsText(ST_Project('POINT(0 0)'::geography, 100000, pi()/4));
+                         st_astext
+------------------------------------------
+ POINT(0.63523102912532 0.63947233472882)
+(1 row)
        </programlisting>
                  </refsection>
 
@@ -3655,7 +3666,7 @@ SELECT ST_AsEWKT(ST_PointOnSurface(ST_GeomFromEWKT('LINESTRING(0 5 1, 0 0 1, 0 1
 
                        <para><xref linkend="ST_Azimuth" />, <xref linkend="ST_Distance" /></para>
                  </refsection>
-               </refentry>
+       </refentry>
 
        <refentry id="ST_Relate">
                <refnamediv>