[gdal-dev] gdal contour, output polygon

[ValiSystem]

that's a very interesting option ! I think i could write a tool in C++ 
to do the grouping, and use the original line strings for the elevation 
lines/text.

thanks a lot


On 12/03/09 17:26, Jamie Adams wrote:
> You could also try using gdal_polygonize 
> <http://www.gdal.org/gdal_polygonize.html>, but you'd need to find a 
> way to reclass your source raster to discrete groups (i.e, elevation 
> ranges).  This could be done pretty easily using python, maybe 
> something like val_repl.py 
> <https://svn.osgeo.org/gdal/trunk/gdal/swig/python/samples/val_repl.py>.
>
> -Jamie
>
> On Wed, Mar 11, 2009 at 12:56 PM, ValiSystem <vali.system at free.fr 
> <mailto:vali.system at free.fr>> wrote:
>
>     Hello !
>
>     I'm trying to generate polygons from gdal contour output. Most of
>     the linestrings generated where closed, so it's not a too bad
>     start. The problem is to define interior and exterior of the
>     polygon : it seems that interior and exterior has no consistent
>     meaning from the linestrings (it makes sense though - a line has
>     no interior nor than exterior).
>
>     So what i need would be a method to recreate the meaning of the
>     polygon : the inside is where i have ground. To make it work, i
>     just would have to transform the polygon to an interior ring of a
>     wider (whole area) polygon when appropriate (when it does not
>     contain a polygon with a higher altitude).
>
>     What do you think about this ? is there a better/known way to
>     achieve that ?
>
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>

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