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update ST_Line_Locate ... with example of closest point. Asked way too many times on postgis news groups

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git-svn-id: http://svn.osgeo.org/postgis/trunk@4341 b70326c6-7e19-0410-871a-916f4a2858ee
This commit is contained in:
Regina Obe 2009-08-01 18:33:18 +00:00
parent adf4763a73
commit 0ed90a2fcc
1 changed files with 30 additions and 14 deletions
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44
doc/reference.xml
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@ -4746,13 +4746,13 @@ GROUP BY gid, field1,field2;
<imagedata fileref="images/check.png" />
</imageobject>
</inlinemediaobject> This function supports 3d and will not drop the z-index.</para>
<!-- Optionally mention Circular String Support -->
<para><inlinemediaobject>
<imageobject>
<imagedata fileref="images/check.png" />
</imageobject>
</inlinemediaobject> This method supports Circular Strings and Curves </para>
<para><inlinemediaobject>
<imageobject>
<imagedata fileref="images/check.png" />
</imageobject>
</inlinemediaobject> This method supports Circular Strings and Curves </para>
</refsection>
@ -9877,7 +9877,7 @@ When densifyFrac is specified, this function performs a segment densification be
<note>
<para>
The current implementation supports only vertices as the discrete locations. This could be extended to allow an arbitrary density of points to be used.
The current implementation supports only vertices as the discrete locations. This could be extended to allow an arbitrary density of points to be used.
</para>
</note>
<note>
@ -9893,18 +9893,18 @@ The current implementation supports only vertices as the discrete locations. Thi
<refsection>
<title>Examples</title>
<programlisting>postgis=# SELECT st_HausdorffDistance(
'LINESTRING (0 0, 2 0)'::geometry,
'MULTIPOINT (0 1, 1 0, 2 1)'::geometry);
<programlisting>postgis=# SELECT st_HausdorffDistance(
'LINESTRING (0 0, 2 0)'::geometry,
'MULTIPOINT (0 1, 1 0, 2 1)'::geometry);
st_hausdorffdistance
----------------------
1
1
(1 row)
</programlisting>
<programlisting>postgis=# SELECT st_hausdorffdistance('LINESTRING (130 0, 0 0, 0 150)'::geometry, 'LINESTRING (10 10, 10 150, 130 10)'::geometry, 0.5);
st_hausdorffdistance
----------------------
70
70
(1 row)
</programlisting>
@ -13246,7 +13246,7 @@ MULTILINESTRING((3 4,4 5),(1 2,3 4))
</refentry>
</sect1>
<sect1 id="Linear_Referencing">
<sect1 id="Linear_Referencing">
<title>Linear Referencing</title>
<refentry id="ST_Line_Interpolate_Point">
<refnamediv>
@ -13311,6 +13311,14 @@ SELECT ST_AsEWKT(ST_Line_Interpolate_Point(the_line, 0.5))
--------------------
POINT(3.5 4.5 5.5)
--find closest point on a line to a point or other geometry
SELECT ST_AsText(ST_Line_Interpolate_Point(foo.the_line, ST_Line_Locate_Point(foo.the_line, ST_GeomFromText('POINT(4 3)'))))
FROM (SELECT ST_GeomFromText('LINESTRING(1 2, 4 5, 6 7)') As the_line) As foo;
st_astext
----------------
POINT(3 4)
</programlisting>
</refsection>
@ -13318,7 +13326,7 @@ SELECT ST_AsEWKT(ST_Line_Interpolate_Point(the_line, 0.5))
<refsection>
<title>See Also</title>
<para><xref linkend="ST_Length" />, <xref linkend="ST_Line_Locate_Point" /></para>
<para><xref linkend="ST_AsText" />,<xref linkend="ST_AsEWKT" />,<xref linkend="ST_Length" />, <xref linkend="ST_Line_Locate_Point" /></para>
</refsection>
</refentry>
@ -13384,6 +13392,14 @@ WHERE ST_DWithin(street_line, house_loc, 0.2);
POINT(1.01 2.06) | 10
POINT(2.02 3.09) | 15
POINT(3.03 4.12) | 20
--find closest point on a line to a point or other geometry
SELECT ST_AsText(ST_Line_Interpolate_Point(foo.the_line, ST_Line_Locate_Point(foo.the_line, ST_GeomFromText('POINT(4 3)'))))
FROM (SELECT ST_GeomFromText('LINESTRING(1 2, 4 5, 6 7)') As the_line) As foo;
st_astext
----------------
POINT(3 4)
</programlisting>
</refsection>