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Re: ColorFunctions again (making z=0 be different from z=1)

  • To: mathgroup at smc.vnet.net
  • Subject: [mg50493] Re: ColorFunctions again (making z=0 be different from z=1)
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Wed, 8 Sep 2004 05:05:43 -0400 (EDT)
  • Organization: Universitaet Leipzig
  • References: <chk0cu$sj$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

a) Hue[] is periodic with its argument with period one and Hue[0] is the
    same as Hue[1] but if you set the color function to
   ColorFunction->(Hue[0.8*#] &) 
   you have romoved the effect

b) the typical colors from Maps are

lscape=Compile[{{v,_Real}},{0.25660999433616455 +
v*(-0.15450689601371334 + 
    v*(16.99064278686296 + v*(-49.77485354775084 + 
        (53.311185629847536 - 20.331201294602224*v)*v))), 
 0.5950036100590319 + v*(0.9030709139591158 + 
    v*(-4.7684534226105955 + v*(39.51236857804843 + 
        v*(-117.41187124896338 + (131.37166677177956 - 
            50.03797646732823*v)*v)))), 0.20815128511236033 + 
  v*(0.911878579970309 + v*(-4.479304425265597 + 
      v*(36.027512397958255 + v*(-101.52716099689235 + 
          (110.30681084859079 - 41.31008420034276*v)*v))))}]
          
LandscapeColor[v_]:=RGBColor @@ lscape[v]          


c)  Look for the Graphics`Legend` standard package and it you don't like
    it the book by Tom Wickham-Jones about Mathematica Graphics has a
nicer
    legend for density and contour plots. The ExtendGraphics package is
    on MathSource

Regards
  Jens

AES/newspost wrote:
> 
> The simple  ColorFunction->Hue  option in Plot3D, ContourPlot, and
> DensityPlot, makes z = 0 appear the same as z = 1 (i.e., both bright
> red), a situation which seems to me to make these plots confusing
> and more difficult to interpret, given that "high peaks" and "sea
> level valleys" may be the most interesting features of such a plot.
> 
> Do others have any favorite, not too messy ColorFunctions that
> make values near z = 0 tend toward white, or grey, or less bright,
> or something so that there's a clearly unidirectional visual
> effect going from values of z near 0 to those near z = 1?
> 
> [And as a side question, a simple Prolog or Epilog code to put
> one of those scaled and labelled vertical color bars alongside a
> ContourPlot or DensityPlot, perhaps with the same vertical
> height as the plot itself?]


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