Need help in 3D plot using MATLAB (X,Y,Z,V)

Question

I need to ask help in plotting a 3D volume in MATLAB. My data set includes the X, Y, Z coordinate and corresponding intensity value, V.

I was using pcolor (X,Y,V) and shading interp while i was doing the 2D images but then I got stuck when I am about to create the 3D images. I have tried scatter3, smooth3 and slice but it seems it does not fit the function I need.

My goal is to plot the 3D grid with the corresponding intensity value per coordinate and apply shading interp between these points.

I am really new in 3D plotting and I would really appreciate any help in achieving my goal. Thank you so much!

Here are some example of images that I am trying to create
_{(source: ndt.net)}

_{(source: www.bam.de)}

Answer 1

I have a solution for your first example, in which you show three cross-sections of the volume data. With this solution you can essentially plot several pcolor with different orientations, in one same 3D figure.

First, you need the data for the different slices. This is exactly what you had when you did pcolor(X,Y,V) to plot the cross section in 2D, where X, Y and V are two dimensional matrices. You will also need to create a matrix Z with the z-position of the slice (e.g. Z = zeros(size(X)) + z0). Then you use the command surface(X,Y,Z,V) to plot the cross section image in 3D, where X,Y,Z are the positions, and V is the color (value of the function).

Repeat this procedure for all the other slices, using appropriate X,Y,Z,V matrices for each slice. For slices oriented on other axes you will have to define X,Y,Z accordingly. Remember to use "hold on" after the first surface command, so that all the slices are plotted.

Example:

surface(X1,Y1,Z1,V1); shading interp; hold on
surface(X2,Y2,Z2,V2); shading interp;
surface(X3,Y3,Z3,V3); shading interp;

colormap(jet(2048)); caxis([0,3]); % color axis colormap and scaling

axis equal; xlabel('X'); ylabel('Y'); zlabel('Z') % X,Y,Z scaling and label

Result figure here: