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update to include ST_Azimuth for geography -- still need example. Also provide example for using degrees

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git-svn-id: http://svn.osgeo.org/postgis/trunk@8641 b70326c6-7e19-0410-871a-916f4a2858ee
This commit is contained in:
Regina Obe 2012-01-01 15:41:10 +00:00
parent 8e697e97b7
commit 9406de8468
1 changed files with 12 additions and 1 deletions
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13
doc/reference_measure.xml
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@ -733,6 +733,11 @@ SELECT ST_Area(the_geog)/POWER(0.3048,2) As sqft_spheroid, ST_Area(the_geog,fal
<paramdef><type>geometry </type><parameter>pointA</parameter></paramdef>
<paramdef><type>geometry </type><parameter>pointB</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>float <function>ST_Azimuth</function></funcdef>
<paramdef><type>geography </type><parameter>pointA</parameter></paramdef>
<paramdef><type>geography </type><parameter>pointB</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsection>
@ -746,16 +751,22 @@ SELECT ST_Area(the_geog)/POWER(0.3048,2) As sqft_spheroid, ST_Area(the_geog,fal
and a point. </para>
<para>Availability: 1.1.0</para>
<para>Enhanced: 2.0.0 support for geography was introduced.</para>
<para>Azimuth is especially useful in conjunction with ST_Translate for shifting an object along its perpendicular axis. See
upgis_lineshift <ulink url="http://trac.osgeo.org/postgis/wiki/UsersWikiplpgsqlfunctions">Plpgsqlfunctions PostGIS wiki section</ulink> for example of this.</para>
</refsection>
<refsection>
<title>Examples</title>
<para>Azimuth in degrees </para>
<para>Geometry Azimuth in degrees </para>
<programlisting>
SELECT ST_Azimuth(ST_Point(25,45), ST_Point(75,100))/(2*pi())*360 as degAz,
ST_Azimuth(ST_Point(75,100), ST_Point(25,45))/(2*pi())*360 As degAzrev;
-- NOTE easier to remember syntax using PostgreSQL built-in degrees function --
-- Both yield same answer --
SELECT degrees( ST_Azimuth(ST_Point(25,45), ST_Point(75,100)) ) as degAz,
degrees( ST_Azimuth(ST_Point(75,100), ST_Point(25,45)) ) As degAzrev;
degaz | degazrev
------------------+------------------