[Qgis-user] Re: How to draw a polygon shapefile around raster pixels?

[Micha Silver]

On 06/16/2010 09:44 PM, nikos ves wrote:
> On Wed, 2010-06-16 at 11:19 -0700, boesiii wrote:
>    
>> How do I add the Raster tools? I don't have the Raster menu.
>>      
> Raster tools will come as default with the next version of qgis which
> will be out in a couple of months.
>
> For now you can install the Raster tools, with the Plugin manager.
> Search them under the name gdal tools or something similar. (try gdal or
> raster, I dont remember atm)
>
>    
You can also try a different approach. You mentioed that you already 
have a raster of slopes and you want vector polygons (? is that your 
goal?) covering everywhere with slope >40.
You can run the GRASS module r.mapcalculator, select the slope raster 
for  raster A then enter A>40 in the equation text box.
The result will be a raster of slopes, but only greater than 40.
Now do r.to.vect to convert to polygons...

-- 
Micha



-- 
Micha Silver
Arava Development Co. +972-52-3665918
http://surfaces.co.il