You could also try using <a href="http://www.gdal.org/gdal_polygonize.html">gdal_polygonize</a>, 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 <a href="https://svn.osgeo.org/gdal/trunk/gdal/swig/python/samples/val_repl.py">val_repl.py</a>. <br>
<br>-Jamie<br><br><div class="gmail_quote">On Wed, Mar 11, 2009 at 12:56 PM, ValiSystem <span dir="ltr"><<a href="mailto:vali.system@free.fr">vali.system@free.fr</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hello !<br>
<br>
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).<br>
<br>
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).<br>
<br>
What do you think about this ? is there a better/known way to achieve that ?<br>
<br>
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