[postgis-users] Some questions concerning postgis

Neil.Young Neil.Young at Freenet.de
Mon Jan 26 23:12:24 PST 2009

Hello Leo and Paul,

thanks for your answers. The data, I have here, consists of 5204 
polygons, each having a common border with some others (screenshot of 
the first half attached). The data requires heavy generalization, 
because it is unnecessary detailed - at least in terms of a planned web 
based vector map presentation (GM, VE, OSM etc.). I guess, simply 
"Douglas-Peuker'ing" each polygon isn't helpful, because splits and 
cavities may be produced by an algorithm, which doesn't mind the 
semantical context of all the polygons. I've found mapshaper.org (which 
isn't working with my data) and this 
I could make the latter run, at least for the first step - the vertex 
creation. Don't know, what results may arise, because it takes hours to 
calculate the things, and I currently have no means to "visualize" the 
results. What would you suggest for visualization? I know mapserver, but 
do I really have to go this way in order to see the table based data?

I'm using SQL Server 2008 normally, there is a in-build viewer. Is 
something similar available for PG?


Paul Ramsey schrieb:
> On Mon, Jan 26, 2009 at 3:54 PM, Paragon Corporation <lr at pcorp.us> wrote:
>> Though if you want to maintain borders I guess you would probably want to
>> 1)  convert your polygons to linestrings using ST_Boundary,
>> 2) dump out into edges and grouping by the gid
>> 3) Simplify and then repolygonize.
> It is hard. Kevin gave a recipe for it once though... perhaps he'll
> wikify it this time...
> P
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