[GRASS-user] Processing Cartosat 1 DEM using GRASS GIS - Reg.

[Jaisen Nedumpala]

2013/3/28 Markus Neteler <neteler at osgeo.org>

> On Wed, Mar 27, 2013 at 2:15 PM, Jaisen Nedumpala <jaisuvyas at gmail.com>
> wrote:
> ..,
> > I have already imported the tiles I want, to the Location and tried
> > r.contour. But It didn't returned the contour.
>
> Please explain what went wrong for you. Error or empty map or ...?
>
> Ah... I made a mistake.. I was importing Cartosat imagery to a UTM
location. :) That's why I didn't get results. I was doing it with Quantum
GIS - GRASS tool box. I corrected it, and got the contour. But the result
is not much impressive comparing with the result got with ASTER DEM. Thank
you...


> It works like this (example: 100m contour lines):
>
> g.region rast=cdnd44h -p
> r.contour input=cdnd44h output=cdnd44h_contours minlevel=-100
> maxlevel=10000 step=100
> d.vect cdnd44h_contours
>
> Or, in the wwGUI:
>
> - load DEM map into layer manager (Add raster map icon)
> - right-mouse on DEM (e.g. cdnd44h): zoom to map
>   --> it will be shown
> - Menu Raster -> Terrain analysis -> Generate contour lines
>   --> r.contour GUI pops up
>
> Required tab:
> - raster map name: cdnd44h
> - output vector map: cdnd44h_contours
>
> Optional tab (entries in meter:
> - minlevel=-100      <-- if not specified, the DEM minimum will be
> used, so better define it
> - maxlevel=10000   <-- if not specified, the DEM maximum will be used,
> so better define it
> - step=100   <-- 100m contour lines
>
> Run button
>
> Likewise for r.watershed and other analytical procedures.
>
> Hope this helps,
> Markus
>



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