[postgis-users] AsKML() how to create kml from postgis data

[Milo van der Linden]

Hold it, stop, take a look at this first!

This post was sent on the mapserver list last friday, please check if 
this will your demands!


http://www.itopen.it/soluzioni/kml-map-server/



Dylan Beaudette schreef:
> On Friday 14 September 2007, John Smith wrote:
>   
>> as_kml()?! there's another askml() in line with asgml(). why this
>> alias/name change/confusion?
>>
>> anyway how does it really work? getting a "Must contain
>> 'geometry_column from table_name' or 'geom from (subselect) as foo'
>> (couldnt find ' from ')". what do i do after passing bbox=... and
>> type=kml to export script? the sql doesn't go inside .map, right? can
>> some share a detailed use/script? not much in
>> http://postgis.refractions.net/docs/postgis.pdf
>>     
>
> I'll add a bit to this discussion, as I have tackled it before.
>
>   
>> btw super example at
>> http://casoilresource.lawr.ucdavis.edu/ka-map/htdocs/?map=casoil&cps=-20125
>> 07.9410234897,-132997.150403761,500000&layers=__base__ 
>>     
>
> Thanks! Here is a shorter link to the corresponding page:
> http://casoilresource.lawr.ucdavis.edu/drupal/node/429
>
>   
>> although i didn't 
>> quite get this part:
>> 1. select geometry overlapping the bounding box defined by the current
>> viewport in AEA coordinates, using the PostGIS spatial indexing system
>> 2. compute the intersection between the boinding box and the
>> overlapping polygons
>> 3. compute the centroids of the new geometry
>> 4. convert the polygon geometry to KML
>> 5. convert the centroid geometry to KML
>> 6. return resulting text
>>     
>
> This is a list of how the PHP code is functioning; some background--
>
> I have a massive table of polygons, stored in a custom AEA projection. Google 
> Earth is not happy about massive KML files, so PostGIS is used to 'cut-out' 
> (intersection) a chunk. This chunk is then converted into KML, with all of 
> the extra XML styling etc. added by a PHP wrapper script. A second pass is 
> done with PostGIS to get the centroids of the polygons, which are used as a 
> labeling mechanism. All of the KML / XML chunks are stuck into a dynamically 
> generated KML document and returned to the user. 
>
> I was able to construct this by
> 1. looking over the KML specs
> 2. looking at some example KML files
> 3. experimentation
>
> Further work should definitely use something other than string functions to 
> build the XML.
>
> Another hint: be sure to send the KML header by PHP first:
>
> 		header("Pragma: public"); // required
> 		header("Expires: 0");       
> 		header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
> 		header("Content-Type: application/kml; charset=utf8");
> 		header('Content-Disposition: attachment; filename="file.kml"') ;
>
>
> check out the examples on the above link, and dissect the resulting KML file 
> for hints.
>
> Cheers,
>
> Dylan
>
>
>
>
>
>   
>> cheers, jzs
>>
>> On 9/14/07, Jose Gomez-Dans <jgomezdans at gmail.com> wrote:
>>     
>>> Hi Maciej,
>>> I sent you an e-mail, but your spam protection system wouldn't allow
>>> the message to go through.  If you have another address, I'll resend
>>> it to you :)
>>>
>>> On 9/14/07, Maciej Skorczewski <maciej.skorczewski at procad.pl> wrote:
>>>       
>>>> how sql should looks like?
>>>>         
>>> Simply (and this is already quite advanced: you can use simplify() to
>>> reduce the number of points in your vector data. Ours are very
>>> detailed, and we don't want that on our KML files):
>>>
>>> SELECT AS_KML(SIMPLIFY(the_geom,100)) from MY_TABLE;
>>>
>>>       
>>>> Question about Python class...i am not python programer can you
>>>> describe my how i can use it?
>>>>         
>>> You just write a small python program to use it. You should be able to
>>> do the same with PHP.
>>>
>>> Cheers,
>>> José
>>>       
>> _______________________________________________
>> postgis-users mailing list
>> postgis-users at postgis.refractions.net
>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>     
>
>
>
>   


-- 


	

Milo van der Linden
skype: milovanderlinden <skype:milovanderlinden?add>
mlinden at zeelandnet.nl <mailto:mlinden at zeelandnet.nl>
milovanderlinden at gmail.com <mailto:milovanderlinden at gmail.com>
milo at 3dsite.nl <mailto:milo at 3dsite.nl>
http://www.3dsite.nl

	  	

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