[GRASS-user] Slope categories from DEM ?

[Emma]

On 6-Nov-10, at 10:41 PM, Martin Landa wrote:

> 2010/11/6 Emma <emma at seleeg.org>:
>> Now I also tried to use r.mapcalc instead of r.reclass as follows:
>> r.mapcalc 'new_slope_30_bis = if(new_slope > 30, 1, 0)'
>>
>> However for some reason the resulting map new_slope_30_bis has:
>> Rows:         20
>> Columns:      20
>> Total Cells:  400
>>
>> while the original new_slope, as well as new_slope_30 have both  
>> Total Cells:
>>  47212692. So you can imagine the result is not very nice...
>
> raster modules operate on the computational region, try to set up the
> region based on slope map before you run r.mapcalc
>
> g.region rast=new_slope
> r.mapcalc ...

Right, this solved the problem! Thanks