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new protos for st_value (the point geometry versions -- yeh) plus examples
git-svn-id: http://svn.osgeo.org/postgis/trunk@5728 b70326c6-7e19-0410-871a-916f4a2858ee
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@ -1293,16 +1293,33 @@ WHERE rid = 2;
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<sect1 id="Raster_Pixel_Accessors">
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<title>Raster Pixel Accessors</title>
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<refentry id="RT_ST_Value">
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<refentry id="RT_ST_Value">
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<refnamediv>
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<refname>ST_Value</refname>
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<refpurpose>Returns the value of a given band in a given columnx, rowy pixel. Band numbers start at 1.</refpurpose>
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<refpurpose>Returns the value of a given band in a given columnx, rowy pixel or at a particular geometric point. Band numbers start at 1 and assumed to be 1 if not specified.</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcprototype>
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<funcdef>double precision <function>ST_Value</function></funcdef>
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<paramdef><type>raster </type> <parameter>rast</parameter></paramdef>
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<paramdef><type>geometry </type> <parameter>pt</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>integer <function>ST_Value</function></funcdef>
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<funcdef>double precision <function>ST_Value</function></funcdef>
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<paramdef><type>raster </type> <parameter>rast</parameter></paramdef>
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<paramdef><type>integer </type> <parameter>bandnum</parameter></paramdef>
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<paramdef><type>geometry </type> <parameter>pt</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>double precision <function>ST_Value</function></funcdef>
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<paramdef><type>raster </type> <parameter>rast</parameter></paramdef>
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<paramdef><type>integer </type> <parameter>columnx</parameter></paramdef>
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<paramdef><type>integer </type> <parameter>rowy</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>double precision <function>ST_Value</function></funcdef>
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<paramdef><type>raster </type> <parameter>rast</parameter></paramdef>
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<paramdef><type>integer </type> <parameter>bandnum</parameter></paramdef>
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<paramdef><type>integer </type> <parameter>columnx</parameter></paramdef>
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@ -1326,18 +1343,30 @@ WHERE rid = 2;
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<para>Also note that many of these examples particular the intersection example can be more
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simply done with the planned functions that are not currently available.</para>
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<para>If you are looking for a function that will take a geometry point and return a pixel value, this is in the works, for now
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you can use a user contributed function <ulink url="http://trac.osgeo.org/postgis/wiki/UsersWikiwktrasterfunctions">upgis_ptval</ulink>
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</para>
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</note>
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</refsection>
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<refsection>
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<title>Examples</title>
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<programlisting>
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SELECt rid, ST_Value(rast, 1,1,1) As b1pval,
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-- get raster values at particular postgis geometry points
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-- the srid of your geometry should be same as for your raster
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SELECT rid, ST_Value(rast, foo.pt_geom) As b1pval, ST_Value(rast, 2, foo.pt_geom) As b2pval
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FROM dummy_rast CROSS JOIN (SELECT ST_SetSRID(ST_Point(3427927.77,5793243.76),-1) As pt_geom) As foo
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WHERE rid=2;
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rid | b1pval | b2pval
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-----+--------+--------
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2 | 252 | 79
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-- general fictious example using a real table
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SELECT rid, ST_Value(rast, 3, sometable.geom) As b3pval
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FROM sometable
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WHERE ST_Intersects(rast,sometable.geom);
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</programlisting>
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<programlisting>
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SELECT rid, ST_Value(rast, 1,1,1) As b1pval,
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ST_Value(rast, 2,1,1) As b2pval, ST_Value(rast, 3,1,1) As b3pval
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FROM dummy_rast
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WHERE rid=2;
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