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update st_union examples (single should always specify band number to be safe) and all bands can be done now with just union

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git-svn-id: http://svn.osgeo.org/postgis/trunk@10374 b70326c6-7e19-0410-871a-916f4a2858ee
This commit is contained in:
Regina Obe 2012-10-04 04:08:36 +00:00
parent fdc512a4f2
commit 7bf0e2f1cd
1 changed files with 16 additions and 5 deletions
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21
doc/reference_raster.xml
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@ -8727,15 +8727,25 @@ UPDATE wind
<programlisting>
-- this creates a single band from first band of raster tiles
-- that form the original file system tile
SELECT filename, ST_Union(rast) As file_rast
SELECT filename, ST_Union(rast,1) As file_rast
FROM sometable WHERE filename IN('dem01', 'dem02') GROUP BY filename;</programlisting>
</refsection>
<refsection>
<title>Examples: Return a multi-band raster that is the union of tiles intersecting geometry</title>
<programlisting>
-- this creates a multi band raster collecting all the tiles that intersect a line
SELECT ST_Union(rast,ARRAY[ROW(1, 'LAST'), ROW(2, 'LAST'), ROW(3, 'LAST')]::unionarg[])
<para>-- this creates a multi band raster collecting all the tiles that intersect a line
-- Note: In 2.0, this would have just returned a single band raster
-- , new union works on all bands by default
-- this is equivalent to unionarg: ARRAY[ROW(1, 'LAST'), ROW(2, 'LAST'), ROW(3, 'LAST')]::unionarg[] </para>
<programlisting>SELECT ST_Union(rast)
FROM aerials.boston
WHERE ST_Intersects(rast, ST_GeomFromText('LINESTRING(230486 887771, 230500 88772)',26986) );</programlisting>
</refsection>
<refsection>
<title>Examples: Return a multi-band raster that is the union of tiles intersecting geometry</title>
<para>Here we use the longer syntax if we only wanted a subset of bands or we want to change order of bands</para>
<programlisting>-- this creates a multi band raster collecting all the tiles that intersect a line
SELECT ST_Union(rast,ARRAY[ROW(2, 'LAST'), ROW(1, 'LAST'), ROW(3, 'LAST')]::unionarg[])
FROM aerials.boston
WHERE ST_Intersects(rast, ST_GeomFromText('LINESTRING(230486 887771, 230500 88772)',26986) );</programlisting>
</refsection>
@ -8746,7 +8756,8 @@ WHERE ST_Intersects(rast, ST_GeomFromText('LINESTRING(230486 887771, 230500 887
<para>
<xref linkend="unionarg" />,
<xref linkend="RT_ST_Envelope" />,
<xref linkend="RT_ST_ConvexHull" />
<xref linkend="RT_ST_ConvexHull" />,
<xref linkend="RT_ST_Clip" />
</para>
</refsection>
</refentry>