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fix some typos, revise example demonstrating difference between intersection and union. include pictures.

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git-svn-id: http://svn.osgeo.org/postgis/trunk@8122 b70326c6-7e19-0410-871a-916f4a2858ee
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Regina Obe 2011-11-09 02:55:40 +00:00
parent 9cf7857f1d
commit d10943d4f5
3 changed files with 39 additions and 9 deletions
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48
doc/reference_raster.xml
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@ -5284,7 +5284,7 @@ WHERE rid=167;
<paramdef choice='opt'><type>text </type> <parameter>extenttype=INTERSECTION</parameter></paramdef>
<paramdef choice='opt'><type>text </type> <parameter>nodata1expr=NULL</parameter></paramdef>
<paramdef choice='opt'><type>text </type> <parameter>nodata2expr=NULL</parameter></paramdef>
<paramdef choice='opt'><type>dobule precision </type> <parameter>nodatanodataval=NULL</parameter></paramdef>
<paramdef choice='opt'><type>double precision </type> <parameter>nodatanodataval=NULL</parameter></paramdef>
</funcprototype>
<funcprototype>
@ -5298,7 +5298,7 @@ WHERE rid=167;
<paramdef choice='opt'><type>text </type> <parameter>extenttype=INTERSECTION</parameter></paramdef>
<paramdef choice='opt'><type>text </type> <parameter>nodata1expr=NULL</parameter></paramdef>
<paramdef choice='opt'><type>text </type> <parameter>nodata2expr=NULL</parameter></paramdef>
<paramdef choice='opt'><type>dobule precision </type> <parameter>nodatanodataval=NULL</parameter></paramdef>
<paramdef choice='opt'><type>double precision </type> <parameter>nodatanodataval=NULL</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
@ -5351,11 +5351,12 @@ WHERE rid=167;
</refsection>
<refsection>
<title>Example: 2 Band Intersection</title>
<title>Example: 2 Band Intersection and Union</title>
<para>Create a new 1 band raster from our original that is a function of modulo 2 of the original raster band.</para>
<programlisting>
--Create a cool set of rasters --
DROP TABLE IF EXISTS fun_shapes;
CREATE TABLE fun_shapes(rid serial PRIMARY KEY, fun_name text, rast raster);
-- Insert some cool shapes around Boston in Massachusetts state plane meters --
@ -5365,7 +5366,7 @@ VALUES ('ref', ST_AsRaster(ST_MakeEnvelope(235229, 899970, 237229, 901930,26986)
INSERT INTO fun_shapes(fun_name,rast)
WITH ref(rast) AS (SELECT rast FROM fun_shapes WHERE fun_name = 'ref' )
SELECT 'area' AS fun_name, ST_AsRaster(ST_Buffer(ST_SetSRID(ST_Point(236229, 900930),26986), 1000),
ref.rast,'8BUI', 118, 0) As rast
ref.rast,'8BUI', 10, 0) As rast
FROM ref
UNION ALL
SELECT 'rand bubbles',
@ -5373,18 +5374,47 @@ SELECT 'rand bubbles',
(SELECT ST_Collect(geom)
FROM (SELECT ST_Buffer(ST_SetSRID(ST_Point(236229 + i*random()*100, 900930 + j*random()*100),26986), random()*20) As geom
FROM generate_series(1,10) As i, generate_series(1,10) As j
) As foo ), ref.rast,'8BUI', 100, 0)
) As foo ), ref.rast,'8BUI', 200, 0)
FROM ref;
--map them -
SELECT st_mapalgebraexpr(
area.rast, bub.rast, 'rast1', NULL, 'INTERSECTION')
SELECT ST_MapAlgebraExpr(
area.rast, bub.rast, 'rast2', '8BUI', 'INTERSECTION', 'rast2', 'rast1') As interrast,
ST_MapAlgebraExpr(
area.rast, bub.rast, 'rast2', '8BUI', 'UNION', 'rast2', 'rast1') As unionrast
FROM
(SELECT rast FROM fun_shapes WHERE
fun_name = 'area') As area
CROSS JOIN (SELECT rast FROM fun_shapes WHERE
fun_name = 'rand bubbles') As bub;
CROSS JOIN (SELECT rast
FROM fun_shapes WHERE
fun_name = 'rand bubbles') As bub
</programlisting>
<informaltable>
<tgroup cols="2">
<tbody>
<row>
<entry><informalfigure>
<mediaobject>
<imageobject>
<imagedata fileref="images/st_mapalgebraexpr2_01.png" />
</imageobject>
<caption><para>mapalgebra intersection</para></caption>
</mediaobject>
</informalfigure>
</entry>
<entry><informalfigure>
<mediaobject>
<imageobject>
<imagedata fileref="images/st_mapalgebraexpr2_02.png" />
</imageobject>
<caption><para>map algebra union</para></caption>
</mediaobject>
</informalfigure>
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</refsection>
<refsection>