[Qgis-user] How to create a slope analysis?

[Marco Hugentobler]

Hi Abbas

You could also use the 'Raster terrain plugin' to calculate slope. The plugin 
comes as a part of the standard installation. Like this, you don't need to use 
the GRASS toolbox (or only if you have more complex analysis tasks).

Then double click the layer to get the raster layer properties dialog, select 
'colormap' as display mode and enter the 4 classes in the 'colormap' tab.

Regards,
Marco

Am Dienstag, 19. Januar 2010 08.14:54 schrieb Micha Silver:
>  Hello Abbas:
> 
>  On 19/01/2010 06:51, badaveil wrote:
> Hi everyone. I'm trying to promote QGIS in Malaysia particularly among
>  govt.agencies.
> 
> 
>  Good to hear.
> 
> I want to create a slope analysis showing 4 class levels of slope gradient
>  so that it can help in processing planning applications by local planning
>  authorities. How does one go about using QGIS to create it? Where can I
>  get reading material on this for QGIS. However, QGIS User Guide 1.3 has
>  not been helpful in the above area.
> 
>  I think your best option is using the GRASS tool (from within QGIS) called
>  r.slope.aspect. You first need, of course, an elevation raster, or DEM.
>  The preferred source today is the ASTER Global DEM data (30 m. resolution
>  all over the globe). This data is available from:
>  https://wist.echo.nasa.gov/ You need to register on the site, choose the
>  ASTER data category, and the region you're interested in, then you can get
>  the raster tiles. They are georeferenced in LatLon WGS84 datum, Geotiff
>  format. Then use the GRASS toolbox to create a slope raster using the
>  r.slope.aspect module.
> 
>  Regards,
>  Micha
> 
> 
>  Thanks
> 
>  Abbas Abdul Wahab
> 
> 
> 
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> 
> 
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-- 
Dr. Marco Hugentobler
HUGIS - GIS programming and consulting
Webereistr. 66
CH-8134 Adliswil
marco at hugis.net
http://homepage.hispeed.ch/hugis/
Technical Advisor QGIS Project Steering Committee