Re: [Matplotlib-users] Basemap to KML polygon

[Lionel R. <lro...@li...>]

Hi Tim,
like I said, I want to "convert" a filled contours map generated with 
Basemap (example here : http://imagebin.ca/view/3nYnN3.html)
to a polygon shapefile (vector). The filled contours are from a regular 
points grid which can already be saved into a point shapefile (via ogr 
python bindings)
and I use QGIS to render it. Now I search to get the filled result into 
a shp file to pass it through "ogr2ogr -f KML" and render it with 
GoogleEarth.
I know I can do all this process with the QGIS-GRASS interface, but I 
must limit softwares dependencies 'cause it'll be placed on a web 
server, and I think Python it's the best choice for doing that :-)
After multiple tests, I can retrieve the polygons points coordinates via 
matplotlib.Patch and save them in a shp file. Now I have troubles with 
"real" coordinates and meta-datas, but nothing impossible :-)

Tim Michelsen a écrit :
>> Looks like I've done a mistake with my last post, sorry Eli...
>> I know how to save datas to a shapefile with the OGR library but only 
>> for points datas.
>>     
>
>
>   
>> I'll appreciate if somebody can point me how to save a filled contour 
>> map basemap into a polygon shapefile, can't find any example with google.
>>     
> What do you really want to save here?
> A basemap with a contour surface overlayed can be viewed as a assembly 
> of various layers. So this is like the result of the gis operations when 
> you launch the map composer to finish your map.
>
> If you want to create a raster file from the contour part plotted over a 
> basemap I think the python bindings of gdal will get you started.
> http://pypi.python.org/pypi/GDAL/
> I succeded into writing a tiff file from a gdal array.
>
> I don't know how to write a vector file from python with ogr or shapely. 
>   But these questions are better to be asked on the gdal list.:
>
> So about interpolating to a contour look at shapely. Writing should be 
> accomplished with ogr.
>
> That said, I only have testing "experience" with writing geodata with 
> python.
>
> The overkill may be to invoke the respective GRASS command by a script.
>
> I would appreciate if you would tell us what you use by the end.
>
> Kind regards,
> Timmie
>
>
> When it comes to python and GIS the first stop seems to be:
>
> * http://gispython.org/
> * http://lists.gispython.org/mailman/listinfo/community
>
> Some more links:
> * http://de.giswiki.net/wiki/Kategorie:Python
> * http://de.giswiki.net/wiki/WorldMill
> * http://zcologia.com/news/750/keytree/
> * http://sgillies.net/
>
>
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Lionel Roubeyrie - lro...@li...
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