MATLAB: Pcolor equivalent for 3D array

3d plot

Hi guys,I want to draw the figure below. I know to use the pcolor function to draw 2D graphics. But now I have a 3D array and I would like a 3D plot of such an array – essentially a 3D cube consisting of 8 "subcubes", with different colors for different numbers just like shown below.

Can anyone help me plot this? Thanks.

Best Answer

The type of plot you've presented is easily reproduced by this:

[x,y,z] = meshgrid(0:3,0:4,0:5);
F = floor(4*rand(size(x)));
szF = size(F);
sq = @(x) squeeze(x);   
surf(sq(x(1,:,:)),sq(y(1,:,:)),sq(z(1,:,:)),sq(F(1,:,:)))   
hold on
surf(sq(x(szF(1),:,:)),sq(y(szF(1),:,:)),sq(z(szF(1),:,:)),sq(F(szF(1),:,:)))
surf(sq(x(:,1,:)),sq(y(:,1,:)),sq(z(:,1,:)),sq(F(:,1,:)))                    
surf(sq(x(:,szF(2),:)),sq(y(:,szF(2),:)),sq(z(:,szF(2),:)),sq(F(:,szF(2),:)))
surf(sq(x(:,:,1)),sq(y(:,:,1)),sq(z(:,:,1)),sq(F(:,:,1)))                    
surf(sq(x(:,:,szF(3))),sq(y(:,:,szF(3))),sq(z(:,:,szF(3))),sq(F(:,:,szF(3))))

After that you might want to adapt the colormap or repeat the plot for displaying other slices in the volume - since this only shows the outer surfaces of a data-cube.

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MATLAB: How to get a slice plot from a 3d surface plot for a particular Z value

I will be happy if you try contour()

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There are some utilities for this on the file exchange, and there is the isocaps function which works with isosurface, but there isn't a builtin utility for adding "skirts" to the surface that the surf function creates.

It's actually relatively easy to do by hand. Here's a simple example:

% Create some interesting sample data
[x,y,z] = peaks;
z = z+3;
x = x(20:end,20:end);
y = y(20:end,20:end);
z = z(20:end,20:end);
[m,n] = size(z);
% Create the original surface
surf(x,y,z);
% Create 4 surfaces around the edges
hold on
walls(1) = surf([x(  1,:); x(  1,:)],[y(  1,:); y(  1,:)],[zeros(1,n); z(  1,:)])
walls(2) = surf([x(end,:); x(end,:)],[y(end,:); y(end,:)],[zeros(1,n); z(end,:)])
walls(3) = surf([x(:,  1), x(:,  1)],[y(:,  1), y(:,  1)],[zeros(m,1), z(:,  1)])
walls(4) = surf([x(:,end), x(:,end)],[y(:,end), y(:,end)],[zeros(m,1), z(:,end)])
set(walls,'FaceColor','interp')

But this only works if all of your Z values are on one side of the origin. If they cross, you need to do something similar to what I described in this blog post about a similar 2D problem.

Best Answer

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MATLAB: How to get a slice plot from a 3d surface plot for a particular Z value

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