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

[Markus Neteler]

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 ...?

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