[GRASS-user] meaning/unit of output of r.relief

[Markus Metz]

On Fri, Dec 21, 2018 at 11:43 AM Moritz Lennert <
mlennert at club.worldonline.be> wrote:
>
> Hello,
>
> Does the numerical output of r.relief have a specific meaning / unit ?

Looking at the code, the meaning is apparently the amount of light falling
onto a given pixel. The units don't matter, the output is meant for display.

More technical: values are computed as

        /* shaded relief */
        cang = sin(altitude) * sin(slp_in_rad) +
               cos(altitude) * cos(slp_in_rad) * cos(azimuth - aspect);

Markus M
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