problems with r.mapcalc
Malcolm Williamson
malcolm at cast.uark.edu
Tue Dec 13 13:11:26 EST 1994
>
> Hello. I have used r.slope.aspect to generate a raster map of
> slopes. The map has labeled each point with slope in degrees.
> I would like to get slope as the tangent of the degrees. I used
> r.mapcalc, and used the equation:
>
> tan.0 = tan(@slope.0)
>
> where tan.0 is my output map and slope.0 is the raster map with
> slopes. However, I get tangent values equal to either zero or
> one, and no fractional values. Can anyone help?
>
> John Stamm
>
Remember, GRASS does not support floating point values in raster layers!
Therefore, you must multiply by some factor. For example:
tan.0 = tan(@slope.0) * 100.0
Hope this works for you.
--
Malcolm D. Williamson - GIS Specialist E-mail: malcolm at cast.uark.edu
Center for Advanced Spatial Technologies Telephone: (501) 575-6159
Ozark Rm. 12 Fax: (501) 575-3846
University of Arkansas
Fayetteville, AR 72701
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