[GRASS-user] r.basin ? for plane geometry of polygon shapefiles

[Margherita Di Leo]

Hi Marco,

On Tue, Jun 5, 2012 at 4:54 PM, Marco Jorge <marco_gjv at ymail.com> wrote:

> Hi,
>
> I have 10k small polygons stored in a shapefile and in raster format (nr
> classes = nr of basins).
> I am interested in getting some planar geometry information for each
> polygon.
>
I have 3 problems, not considering the lack of knowledge:
>
> - no DTM;
> - no channels;
> - try to foul r.basin with the shapefile
>
> Can you think of a way to pick the module and its code to calculate the
> indices in the end of the post?
> Can anyone point me a way to pick up the major axis instead of the lenght
> of the main channel ?
> Any hint on major (or minor) axis extraction?
>
> Should I try other approach?
>

To me, it's not clear what you are trying to get. If your aim is to perform
a hydrological analysis, you do need a DEM, and you can easily download
i.e. an ASTER GDEM for your area and then use r.basin. If your analysis
it's not related to hydrology, and you just need some "shape indexes", what
you should do is probably related to what you are trying to achieve..  Can
you explain a little more?

Regards,
madi


-- 
Dr. Margherita Di Leo
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20120607/5c96b891/attachment-0001.html>