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MathGroup Archive 2004

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Re: ListDensityPlot, ColorFunction, and associated confusions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg49837] Re: ListDensityPlot, ColorFunction, and associated confusions
  • From: "Peltio" <peltio at twilight.zone>
  • Date: Tue, 3 Aug 2004 01:11:09 -0400 (EDT)
  • References: <cear75$asf$1@smc.vnet.net>
  • Reply-to: "Peltio" <peltioNOSP at Mdespammed.com.invalid>
  • Sender: owner-wri-mathgroup at wolfram.com

"AES/newspost" wrote

>I'm trying to show some rectangular arrays in two ways by creating
>side-by-side ListPlot3D and ListDensityPlot displays in a GraphicsArray.
>
>Each of the arrays contains a primary "mountain peak" that arises out of
>a flat plane at a base elevation close to zero, plus several secondary
>hillocks only 1/3 to 1/2 as high as the main peak -- and that's how they
>show up in the ListPlot3D,
>
>In the ListDensityPlot, however, using the standard ColorFunction->Hue,
>the tops of some of the secondary hillocks show up in the same bright
>red as the top of the main peak, even though they appear in the
>ListPlot3D to be less than 1/2 as high as the main peak.  It's as if
>ColorFunctionScaling is being applied locally to each individual peak
>somehow.

Advice from Selwyn Hollis and Hartmut Wolf has prolly solved your problem,
but I'd rather add a little footnote, if I may do so.
If ListDensityPlot stands to ListPlot3D as DensityPlot stands to Plot3D, a
difference in the plot's colors can be traced back to the different way
these procedures handle the values to be plotted.
The color of a DensityPlot 'tile' is given by the value at its center; the
color of a Plot3D 'tile' is given by the values at its four corners.

If this 'staggering' is kept in their list counterparts, it could cause some
further color discrepancy. And in this case I'm afraid there's no simple
scaling function to make them the same.

cheers,
Peltio
my two cents.
--
Invalid address in reply-to. Crafty demunging required to mail me.


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