[postgis-users] gis noob question

Iulian Margarintescu eti at erata.net
Tue Nov 4 07:16:29 PST 2008


I have a collection of shapefiles for a number of zipcodes witch i 
already imported to postgres, and with i need to use them to create a 
map with ThinkGeo. Loading all the data in ThinkGeo (the same in uDig) 
works but really slow ( also slow when loading shapefiles directly ). 
After some research i've found out about simplification algorithms and 
at first tried to simplify every shape for every zipcode but when 
displayed there are a lot of gaps between shapes. Than i've found out 
about topology preserving simplification but i does not make a lot of 
sense to apply the algorithm for each shape, and if applyed for a 
collection of shapes it would be nice if after the simplification i 
still have a shape for each zipcode since i have data attached to the 

Now my question is how should i apply this topology preserving 

Is it sane to do something like this (with a lot of zipcodes):

select geom(st_dump(
    (select  ST_SimplifyPreserveTopology ( st_collect(the_geom),0.01) 
from zipcodes

Any other ideas on how should i approach this ?

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