Change colour of data points on 3D Matlab Plot based on distance from origin

Question

I have x,y,z position data that I want to plot in a 3d MATLAB plot however I want to alter the colour of the data points based on their distance from the origin. My current code as part of this script is:

figure

% Initialise plot, get handle to object and set style to dots
h = plot3(NaN,NaN,NaN,'.'); 
% Fix axes
axis([min(X3D(:)) max(X3D(:)) min(Y3D(:)) max(Y3D(:)) min(Z3D(:)) max(Z3D(:))]); 

% Loop over all elements of XS3D
for ii = 1:length(X3D)
    % pause for animation behaviour
    pause(0.01)
    % Set data of graph
    set(h, 'XData', X3D(1:ii), 'YData', Y3D(1:ii), 'ZData', Z3D(1:ii));      
end

Of course, this only plots the data points with a single colour at all times which is not what I want.

I should note that I achieved this in a 2D plot, albeit with discrete colour changes not continuous, as shown below:

%Plot starts here
figure

% Set x and y limits of the plot
xlim([min(X(:))-1 max(X(:))+1])
ylim([min(Y(:))-1 max(Y(:))+1])

% Plot point by point
for k = 1:numel(X)
    if (X(k)^2 + Y(k)^2) < 500
        plot(X(k),Y(k),'.g') 

    elseif (X(k)^2 + Y(k)^2) >= 500 && (X(k)^2 + Y(k)^2 < 1000)
        plot(X(k), Y(k),'.','color',orange)

    else
        plot(X(k), Y(k), '.r')
    end

% MATLAB pauses for 0.001 sec before moving on to execute the next 
% instruction => thus creating animation effect
pause(0.001);  

end

However the above only seems to work for 2d plots, if I try code similar to this where I swap plot to plot3 I still do not get a 3d plot for some reason.

You should look into scatter3. With the fifth input argument C you can specify options for the color. — mikkola

Anton Anton · Accepted Answer · 2015-12-21T08:51:08

As mentioned above you can use the scatter3 plot.

X3D=rand(1, 1000);
Y3D=rand(1, 1000);
Z3D=rand(1, 1000);

%define colors as distance to the origin
C = sqrt(X3D.^2+Y3D.^2+Z3D.^2);
%scale the colors to 0<=C<=1
C = C/max(C);

figure

% Initialise plot, get handle to object and set style to dots
h = scatter3(NaN,NaN,NaN); 
colormap(jet);
% Fix axes
axis([min(X3D(:)) max(X3D(:)) min(Y3D(:)) max(Y3D(:)) min(Z3D(:))     max(Z3D(:))]); 

pointSize = 3;

% Loop over all elements of XS3D
for ii = 1:length(X3D)
    % pause for animation behaviour
    pause(0.01)
    % Set data of graph
    set(h, 'XData', X3D(1:ii), 'YData', Y3D(1:ii), 'ZData', Z3D(1:ii), 'SizeData', pointSize, 'CData', C(1:ii));      
end

Here is the result:

Change colour of data points on 3D Matlab Plot based on distance from origin

1 Answers