[Gvsig_english] Field calculator::possibility to calculate x/y coordinates?

[Antonio Falciano]

Hi Wolfgang,
I'm agree with you. I think that we all prefer a simple button to make
these operations.
A good approach/algorithm could be:
http://local.wasp.uwa.edu.au/%7Epbourke/geometry/polyarea/
but we need a way to obtain the coords of the single vertices...
I think to the OGC Simple Feature Specifications in WKT format...
extract coords by this string and apply the right formulas!
In pseudo code, it seems too easy... :)

Regards,
Antonio


Wolfgang Qual ha scritto:
> Hi Antonio, list,
> thanks for this idea, Antonio! However, I would prefer to have a script, 
> function, button etc. within gvSIG for Shapefiles. At the moment, we do not 
> even have a PostGIS-database in our office. Could imagine that it would be a 
> very nice example for the create-an-extension-capabilities in gvSIG. Ideas 
> are welcome!
> 
> Best,
> Wolfgang
> 
> 
> Am Dienstag 11 September 2007 pH:07:10 vormittags schrieb Antonio Falciano:
>> Wolfgang Qual wrote:
>> [...]
>>
>>> Therefore, my question should be a different one: is there a possibility
>>> to identify the centres of gravity for a polygon theme?
>> Hi Wolfgang,
>> you can do it simply using PostGIS. You have to:
>> 1. export your polygon theme to PostGIS;
>> 2. create a view in which you calculate centroids coords;
>> 3. add view in gvSIG as layer or table from PostGIS.
>>
>> Regards,
>> Antonio Falciano
>>
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>