[GRASS-user] Slope categories from DEM ?

[Daniel Victoria]

Rich,

The if syntax in r.mapcalc is as follows:

if(test condition, response if true, response if false)

So, by reversing the test in the if statement will give you values of
1 for low slope areas.

Check out the r.mapcalc man page for the complete if syntax

Daniel

On Sat, Nov 6, 2010 at 4:06 PM, Rich Shepard <rshepard at appl-ecosys.com> wrote:
> On Sat, 6 Nov 2010, Martin Landa wrote:
>
>> r.mapcalc 'slope_30 = if(slope_map > 30, 1, 0)'
>>
>> r.mapcalc generates raster map with two values - 1 for areas where slope
>> is greater then 30% and 0 for areas where slope is lower or equal then
>> 30%.
>
> Martin,
>
>  Is the reverse 'slope_30 = if(slope_map < 30, 1, 0)' mean that areas = 1
> are < than 30% and areas with 0 are >= 30%?
>
>  My question is the value of areas where slope = 30% are placed with the
> different mapcalc expressions.
>
> Thanks,
>
> Rich
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