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@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