Re: Coloring a ListSurfacePlot3D with a n x 4 matrix
- To: mathgroup at smc.vnet.net
- Subject: [mg118274] Re: Coloring a ListSurfacePlot3D with a n x 4 matrix
- From: David Kahle <david.kahle at gmail.com>
- Date: Tue, 19 Apr 2011 06:58:17 -0400 (EDT)
Hi Bob!
Thanks for the reply.
Unfortunately, since I only have the points in the matrix I don't know
what the underlying function is. I tried to get around the problem
with Interpolation, but Interpolation (for some reason) wasn't able to
make a function that I could then pass to ListSurfacePlot3D. So I
tried with BSplineFunction, but that didn't work either but for a
different reason (mis-specification problem?).
Ideas? Code below.
Thanks again
david.
points = Flatten[
Table[{x, y, 1 - x - y, (x - 1/2)^2 + (y - 1/2)^2 + RandomReal[]},
{x, 0,
1, 1/4}, {y, 0, 1, 1/4}], 1];
knots = Most /@ points;
values = Last /@ points;
list4interpolation = Table[{knots[[k]], values[[k]]}, {k,
Length[knots]}];
intF = Interpolation[list4interpolation] (* fails *)
f = BSplineFunction[points];
colorF = Function[{x, y, z}, ColorData["GreenBrownTerrain"]@f[x, y, z]];
ListSurfacePlot3D[knots, ColorFunction -> colorF]
On Apr 18, 2011, at 5:37 AM, Bob Hanlon wrote:
>
> The ColorFunction must be defined for all values of {x,y,z} not just
> discrete values.
>
> points = Flatten[Table[
> {x, y, 1 - x - y, (x - 1/2)^2 + (y - 1/2)^2},
> {x, 0, 1, 1/4}, {y, 0, 1, 1/4}], 1];
>
> knots = Most /@ points;
>
> colorF = Function[{x, y, z},
> ColorData["GreenBrownTerrain"][
> (x - 1/2)^2 + (y - 1/2)^2]];
>
> ListSurfacePlot3D[knots, ColorFunction -> colorF]
>
>
> Bob Hanlon
>
> ---- David Kahle <david.kahle at gmail.com> wrote:
>
> =============
> Hi all -
>
> I have a matrix whose rows, 4 dimensional vectors, represent (x, y, z)
> values as well as a measurement f which I would like to use to create
> an interpolated surface colored according to the value of f.
> ListSurfacePlot3D gives me the appropriate surface (when I strain out
> the x, y, z values), but I'm having a hard time coloring it. I've
> tried basic stuff with ColorFunction to no avail, but I'm sure this is
> a simple task. Ideas? Small example below.
>
>
> Points = Flatten[
> Table[{x, y, 1 - x - y, (x - 1/2)^2 + (y - 1/2)^2}, {x, 0, 1,
> 1/4}, {y, 0,
> 1, 1/4}], 1];
> N[Points[[1 ;; 5]]]
>
> Knots = Map[Take[#, {1, 3}] &, Points];
> N[Knots[[1 ;; 5]]]
>
> ListSurfacePlot3D[Knots] (* Works fine, how to I color the surface? *)
>
> Colorf = Function[{x, y, z}, ColorData["GreenBrownTerrain"][
> Points[[ Position[Knots, {x, y, z}][[1]] ]][[1]][[4]]
> ]];
> ListSurfacePlot3D[Knots, ColorFunction -> Colorf]
>
>
> Many thanks
> david.
>
> ----------------------------------
> ----------------------------------
> David Kahle
> Rice University
> Rm. 1041 Duncan Hall
> Department of Statistics, MS 138
> 6100 Main St.
> Houston, TX 77005
> http://sites.google.com/site/davidkahle
>
>