[GRASSLIST:5083] Re: surface roughness scale and colortable

H. Bowman ihatejunkyabastards at yahoo.com
Wed Nov 27 04:19:48 EST 2002

> 1 - a few days ago, I posted a question about how to calculate the
> surface roughness of an area. After a little brainstorm I did it. thanks
> to all who answer, special to Thorsten Behrens and Eric Miller.

May I ask what worked?

> Now I have a new problem with my recently-created roughness map: When I 
> compare it with other similar map made with Arcview, I see that there's
> a little difference in the scale of the roughness. In the arcview's map,
> the scale goes from 1 (planar area) to 1.23, but in the GRASS's map, it 
> goes
> from 0 (planar area) to 67. I guess I have o normalise the values, but I
> don't know how. Any ideas?

If you want 67 to be 1.23, and 0 to be 1, try something like:
r.mapcalc newmap='1+(oldmap*(0.23/67))'

> 2 - About the colortables (i guess this one is easy...): how can I set
> my own colortable? I mean, it's not about changing the colortable using
> the predefined ones (rainbow, red thru yellow, etc)?

have a look at the files in $mapset/colr after setting different colors=, 
and read the r.colors man page. I found it easiest to edit those files by 

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