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seen Nov 8 '12 at 11:01

Oct
31
comment Getting ST_Difference between two different tables in postgis
that url might not work: try this tinypic.com/r/2ut6kqc/6 You can see the individual sqaures within the cropped islands. I just need to union the squares within each island into a single polygons
Oct
31
comment Getting ST_Difference between two different tables in postgis
Hi, Sorry for not uploading picture. I couldn't figure out how to do it. Its ok I had to crack on and get it finished, so I just wrote some .net code to run it as a batch process. However I'm now trying to union the data and that is also taking a long time. A screen shot is here of what it looks like [IMG]i46.tinypic.com/2ut6kqc.png[/IMG] and the sql i'm trying to use is this: Select st_union(density_square_islands.islands) into density_square_islands_union from density_square_islands where st_touches(density_square_islands.islands,density_square_islands.islands); thanks
Oct
30
comment Getting ST_Difference between two different tables in postgis
could you give me an example or pseudocode about how to use intersect first? Only I did try something like this but the output was still seperate versions of the main polygon each with a single voronoi cut out. its like I want to crop single geometry against whole table, but the functions want to crop each geometry against each geometry, hence the duplication.
Oct
30
awarded  Student
Oct
30
asked Getting ST_Difference between two different tables in postgis