[postgis-commits] svn - r2934 - trunk/doc
postgis-commits at postgis.refractions.net
postgis-commits at postgis.refractions.net
Thu Sep 4 04:56:49 PDT 2008
Author: robe
Date: 2008-09-04 04:56:48 -0700 (Thu, 04 Sep 2008)
New Revision: 2934
Modified:
trunk/doc/reference.xml
trunk/doc/reference_new.xml
Log:
Move over ST_Overlaps to new reference section and provide some examples
Modified: trunk/doc/reference.xml
===================================================================
--- trunk/doc/reference.xml 2008-08-30 16:36:43 UTC (rev 2933)
+++ trunk/doc/reference.xml 2008-09-04 11:56:48 UTC (rev 2934)
@@ -25,29 +25,6 @@
<variablelist>
<varlistentry>
- <term>ST_Overlaps(A geometry, B geometry)</term>
-
- <listitem>
- <para>Returns TRUE if the Geometries "spatially
- overlap".</para>
-
- <para>Performed by the GEOS module</para>
-
- <para>Do not call with a GeometryCollection as an argument</para>
-
- <para>This function call will automatically include a bounding box
- comparison that will make use of any indexes that are available on
- the geometries. To avoid index use, use the function
- _ST_Overlaps.</para>
-
- <para>NOTE: this is the "allowable" version that returns a
- boolean, not an integer.</para>
-
- <para>OGC SPEC s2.1.1.2 // s2.1.13.3</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
<term>ST_Contains(A geometry, B geometry)</term>
<listitem>
@@ -2178,17 +2155,6 @@
</varlistentry>
<varlistentry>
- <term>ST_Overlaps</term>
-
- <listitem>
- <para>Test if an ST_Geometry value spatially overlays another
- ST_Geometry value.</para>
-
- <para>SQL-MM 3: 5.1.32</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
<term>ST_Point</term>
<listitem>
Modified: trunk/doc/reference_new.xml
===================================================================
--- trunk/doc/reference_new.xml 2008-08-30 16:36:43 UTC (rev 2933)
+++ trunk/doc/reference_new.xml 2008-09-04 11:56:48 UTC (rev 2934)
@@ -3937,13 +3937,104 @@
f
(1 row)
</programlisting>
+ </refsection>
+ <refsection>
+ <title>See Also</title>
+ <para><xref linkend="ST_Equals"/></para>
+ </refsection>
+ </refentry>
+
+ <refentry id="ST_Overlaps">
+ <refnamediv>
+ <refname>ST_Overlaps</refname>
+
+ <refpurpose>Returns TRUE if the Geometries share space, are of the same dimension, but are not completely contained by each other.</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>boolean <function>ST_Overlaps</function></funcdef>
+ <paramdef><type>geometry </type> <parameter>A</parameter></paramdef>
+ <paramdef><type>geometry </type> <parameter>B</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+
+ <refsection>
+ <title>Description</title>
+
+ <para>Returns TRUE if the Geometries "spatially
+ overlap". By that we mean they intersect, but one does not completely contain another. </para>
+
+ <para>Performed by the GEOS module</para>
+
+ <note><para>Do not call with a GeometryCollection as an argument</para></note>
+
+ <para>This function call will automatically include a bounding box
+ comparison that will make use of any indexes that are available on
+ the geometries. To avoid index use, use the function
+ _ST_Overlaps.</para>
+
+ <para>NOTE: this is the "allowable" version that returns a
+ boolean, not an integer.</para>
+
+ <para>OGC SPEC s2.1.1.2 // s2.1.13.3</para>
+
+ <para>
+ <inlinegraphic class="sql_mm_compliant" fileref="images/check.png" />
+ This method implements the SQL/MM specification: SQL-MM 3: 5.1.32
+ </para>
+
</refsection>
+
+ <refsection>
+ <title>Examples</title>
+
+ <programlisting>--a point on a line is contained by the line and is of a lower dimension, and therefore does not overlap the line
+ nor crosses
+
+SELECT ST_Overlaps(a,b) As a_overlap_b,
+ ST_Crosses(a,b) As a_crosses_b,
+ ST_Intersects(a, b) As a_intersects_b, ST_Contains(b,a) As b_contains_a
+FROM (SELECT ST_GeomFromText('POINT(1 0.5)') As a, ST_GeomFromText('LINESTRING(1 0, 1 1, 3 5)') As b)
+ As foo
+
+a_overlap_b | a_crosses_b | a_intersects_b | b_contains_a
+------------+-------------+----------------+--------------
+f | f | t | t
+--a line that is partly contained by circle, but not fully is defined as intersecting and crossing,
+-- but since of different dimension it does not overlap
+SELECT ST_Overlaps(a,b) As a_overlap_b, ST_Crosses(a,b) As a_crosses_b,
+ ST_Intersects(a, b) As a_intersects_b,
+ ST_Contains(a,b) As a_contains_b
+FROM (SELECT ST_Buffer(ST_GeomFromText('POINT(1 0.5)'), 3) As a, ST_GeomFromText('LINESTRING(1 0, 1 1, 3 5)') As b)
+ As foo;
+ a_overlap_b | a_crosses_b | a_intersects_b | a_contains_b
+-------------+-------------+----------------+--------------
+ f | t | t | f
+
+ -- a 2-dimensional bent hot dog (aka puffered line string) that intersects a circle,
+ -- but is not fully contained by the circle is defined as overlapping since they are of the same dimension,
+-- but it does not cross, because the intersection of the 2 is of the same dimension
+-- as the maximum dimension of the 2
+
+SELECT ST_Overlaps(a,b) As a_overlap_b, ST_Crosses(a,b) As a_crosses_b, ST_Intersects(a, b) As a_intersects_b, ST_Contains(b,a) As b_contains_a, ST_Dimension(a) As dim_a, ST_Dimension(b) as dim_b
+FROM (SELECT ST_Buffer(ST_GeomFromText('POINT(1 0.5)'), 3) As a, ST_Buffer(ST_GeomFromText('LINESTRING(1 0, 1 1, 3 5)'),0.5) As b)
+ As foo;
+
+a_overlap_b | a_crosses_b | a_intersects_b | b_contains_a | dim_a | dim_b
+------------+-------------+----------------+--------------+-------+-------
+t | f | t | f | 2 | 2
+</programlisting>
+ </refsection>
+
<refsection>
<title>See Also</title>
- <para><xref linkend="ST_Equals"/>, <xref linkend="ST_Reverse"/></para>
+ <para><xref linkend="ST_Contains"/>, <xref linkend="ST_Crosses"/>, <xref linkend="ST_Intersects"/></para>
</refsection>
</refentry>
<refentry id="ST_Perimeter">
More information about the postgis-commits
mailing list