[GRASS-user] Help using color tables (differences)

[Thomas Adams]

List:

I have been using r.colors -n map=mapname color=differences to display 
soil moisture differences from one day to another (to identify areas 
that have received precipitation and areas that are drying); I would 
like to depict wetting areas as shades of blue to white and drying areas 
as shades of white to red — as the the option color=differences tries to 
do. The difficulty I'm running into is that unless there is a fairly 
even proportion of of positive & negative values I'll have wetting areas 
colored a shade of red instead of blue, but more often, the reverse 
where drying areas are colored blue, due to the shift of the color 
scale. Ideally, I want values close to -0- to be white and wet areas to 
be a shade of blue and dry areas to be a shade of red. How can I do 
this? Any suggestions?

Thanks,
Tom

-- 
Thomas E Adams
National Weather Service
Ohio River Forecast Center
1901 South State Route 134
Wilmington, OH 45177

EMAIL:	thomas.adams at noaa.gov

VOICE:	937-383-0528
FAX:	937-383-0033