[postgis-users] polygon Extraction problem

[Clay, Bruce]

I have a table of points extracted from a raster file. I perform the following SQL on the table 

CREATE TABLE weather_poly as

SELECT(pixel_val, ST_Transform(ST_Union(ST_Buffer(shape, 0.1)),4326)) FROM

weather_points GROUP BY pixel_val;

The resulting polygon is 13 multi-polygons one for each pixel value instead of one polygon for every cluster of points.

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.

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.

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?

Bruce




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