How to create 3D contour plot of a set of data consisting of series of points x,y,z with a quantity V(x,yz)?

I have a set of data consisting of coordinates x,y,z and the value of a quantity V at each of these points.

like

x,y,z,V

1,3,5,9

3,5,7,-9

......

-4,6,2,1

I need to plot contours of V at the coordinates x,y,z. the number of different x values is NOT equal to the number of different y values.

Any help would be appriciated.

Thank you

Answer 1

[Shivam]

Hi @NAFTALI HERSCOVICI,

You can plot contours of V at the coordinates (x, y, z) by following the below mentioned workaround:

1. Use scatteredInterpolant to interpolate the scattered data onto a regular grid.
2. Then, plot the 3D contour slices of V using contourslice function.

% Sample data for demonstration
x = rand(20, 1) * 10;
y = rand(20, 1) * 10;
z = rand(20, 1) * 10;
V = sin(x) + cos(y) + z;

% Create a grid and interpolate
[xq, yq, zq] = meshgrid(linspace(min(x), max(x), 50), linspace(min(y), max(y), 50), linspace(min(z), max(z), 50));
F = scatteredInterpolant(x, y, z, V, 'linear', 'none');
Vq = F(xq, yq, zq);

% Plot 3D contours
figure;
contourslice(xq, yq, zq, Vq, [], [], linspace(min(z), max(z), 10));


xlabel('X');
ylabel('Y');
zlabel('Z');
title('3D Contour Plot of V');
colorbar;
grid on;
view(3);

For more info regarding the meshgrid, scatteredInterpolant and contourslice function, you can visit these official MATLAB documentations:

1. https://www.mathworks.com/help/matlab/ref/meshgrid.html
2. https://www.mathworks.com/help/matlab/ref/scatteredinterpolant.html
3. https://www.mathworks.com/help/matlab/ref/contourslice.html

I hope this demonstration helps you with your data.

[NAFTALI HERSCOVICI]

Thanks, your code works just fine as is. the issue is that size of X is NOT equal to the size of Y. I tried this case and the dode failed.