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Hi Bruce,<br>
<br>
if you use ST_Dump like this, the resulting data type will be an
array consisting of geometrie and path (internal number of the
polygon). In order to just get the geometries, you would have to use
this kind of query:<br>
<br>
select (st_dump(shape)).geom as the_geom from weather_poly;<br>
<br>
If you're writing this in a new table you will be able to access it
with QGIS.<br>
<br>
Regards,<br>
<br>
Birgit.<br>
<br>
<br>
Am 27.10.2011 04:06, schrieb Clay, Bruce:
<blockquote
cite="mid:C482FF98AE985A47B8C982FD429C9E34D8C01C@daytonmsg2k3.AERO.BALL.COM"
type="cite">
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<div><font size="2" face="Arial" color="#000000">
<p style="MARGIN-BOTTOM: 5pt; MARGIN-LEFT: 0in; MARGIN-RIGHT:
0in" class="MsoNormal"><span style="FONT-FAMILY:
'Arial','sans-serif'; COLOR: black; FONT-SIZE: 10pt">I
have a table of points extracted from a raster file. I
perform the following SQL on the table</span><span
style="FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE:
12pt"> </span></p>
<p style="MARGIN-BOTTOM: 5pt; MARGIN-LEFT: 0in; MARGIN-RIGHT:
0in" class="MsoNormal"><span style="FONT-FAMILY:
'Arial','sans-serif'; FONT-SIZE: 10pt">CREATE TABLE
weather_poly as</span></p>
<p style="MARGIN-BOTTOM: 5pt; MARGIN-LEFT: 0in; MARGIN-RIGHT:
0in" class="MsoNormal"><span style="FONT-FAMILY:
'Arial','sans-serif'; FONT-SIZE: 10pt">SELECT(pixel_val,
ST_Transform(ST_Union(ST_Buffer(shape, 0.1)),4326)) FROM</span></p>
<p style="MARGIN-BOTTOM: 5pt; MARGIN-LEFT: 0in; MARGIN-RIGHT:
0in" class="MsoNormal"><span style="FONT-FAMILY:
'Arial','sans-serif'; FONT-SIZE: 10pt">weather_points
GROUP BY pixel_val;</span></p>
<p style="MARGIN-BOTTOM: 5pt; MARGIN-LEFT: 0in; MARGIN-RIGHT:
0in" class="MsoNormal"><span style="FONT-FAMILY:
'Arial','sans-serif'; FONT-SIZE: 10pt">The resulting
polygon is 13 multi-polygons one for each pixel value
instead of one polygon for every cluster of points.</span></p>
<p style="MARGIN-BOTTOM: 5pt; MARGIN-LEFT: 0in; MARGIN-RIGHT:
0in" class="MsoNormal"><span style="FONT-FAMILY:
'Arial','sans-serif'; FONT-SIZE: 10pt">I can run the
following SQL select ST_Dump(shape) from weather_poly a to
break the polygons so they appear as separate polygons in
Postgresql data view.</span></p>
<p style="MARGIN-BOTTOM: 5pt; MARGIN-LEFT: 0in; MARGIN-RIGHT:
0in" class="MsoNormal"><span style="FONT-FAMILY:
'Arial','sans-serif'; FONT-SIZE: 10pt">When I try to view
them in QGis the table does not show on the list of
available PostGis layers. The properties of the table in
Postgresql show the geometry to be ST_Dump not polygon.</span></p>
<p style="MARGIN-BOTTOM: 5pt; MARGIN-LEFT: 0in; MARGIN-RIGHT:
0in" class="MsoNormal"><span style="FONT-FAMILY:
'Arial','sans-serif'; FONT-SIZE: 10pt">Is there a way to
split the multi-polygon into individual polygons or to
build the original polygons separatly so they will show in
QGis and be accessable as such by GDAL based applications?</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:
'Arial','sans-serif'; FONT-SIZE: 10pt">Bruce</span></p>
</font></div>
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