How to plot 3D using a table

Question

Mad Gano 2022-6-27

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评论： William Rose 2022-7-5

I have for example this table

I would like to plot this table 3D so that the values in between have to be interpreted with respect to the balloon size but also with smooth color change (here I use e.g. colormap(jet)).

P.s

Actually I can't understand the surf(X,Y,Z,C) because X,Y,Z are only vectors and C can't be defined.

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Answer 1

William Rose 2022-6-27

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@Mad Gano,

Please sypply your data as a mat file or text file instead of an image. Thank you.

I do not understand your goal. Do you want to plot spheres of different radii and colors, with centers at the specified x,y,z values? If so, it appears that there will b a number of pairs of balloons that mostly overlap eachother.

Do the specified x,y,z points represent samples of a surface, and you want to interpolate to get other points on the surface? If so, then you might be able to interpolate z values at other x,y locations, or you can interpolate radii or colors at other x,y locations, or you can do all three, but those interpolations must be done independently. Is that your goal? If it is your goal, then it will be difficult, because the distribution of points in the table is very uneven in the x-y plane. X values range from 1.41 to 3.66, but are unevenly spread. Y values are also unevenly spread: y=4.69 (n=2), y=6.56 (n=7), y=8.36 (n=1), y=8.44 (n=25).

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William Rose 2022-6-29

在 MATLAB Online 中打开

@Mad Gano,

%plotColoredSpheres.m

%W. Rose 2022

clear

A=importdata('ColorMix2.txt'); %read data from file

xc=A.data(:,1); yc=A.data(:,2); zc=A.data(:,3); %center coordinates

vol=A.data(:,4); %volumes

BallColor=A.data(:,5); %colors

r=(vol*3/(4*pi)).^(1/3); %radii

figure;

for i=1:length(xc)

%Next: Create arrays for sphere with 6x6 faces

[xs,ys,zs]=sphere(6);

%Next: Adjust sphere radius and position to desired values

xs=xs*r(i)+xc(i); ys=ys*r(i)+yc(i); zs=zs*r(i)+zc(i);

cs=BallColor(i)*ones(size(zs)); %color for sphere

surf(xs,ys,zs,cs); %plot one sphere

hold on

end

axis equal

xlabel('X'); ylabel('Y'); zlabel('Z'); %axis labels

colorbar %add color bar to plot

The last line of file ColorMix.txt has a sphere that is far away from all the other spheres. Inclusion of that sphere in the plot makes the others look tiny and squished into one corner. Therefore I deleted the last line of ColorMix.txt and saved the edited file as ColorMix2.txt. If you want to see the result with the outlier sphere, edit the file name in line 1 to 'ColorMix.txt'.

When you run the code in Matlab, you will be able to click and drag in the plot, to rotate the plot in 3D.

Good luck!

William Rose 2022-6-30

@Mad Gano, Here is an example of an FEM result, in which a value such as stress is known at each point in a mesh, and the plot shows that stress as color, interpolated across the mesh. It is from this discussion.

Is this what you want? The plot above is for a 2D mesh, but your nodes are in 3D. There is no easy way to plot stress with color in 3D, because that makes a 4D plot (x,y,z,stress). You can do it by a) plotting stress on a plane that slices through the 3D volume, or b) by plotting stress on a surface that exists in 3D.

If you want a), then you need to interpolate in 3D. Matlab's interp3() does that, but the input data needs to be defined at all points on a 3D grid of points, and yours is not. You will also need to define the plane of the slice. This can be done by specifying 3 locations in the plane, or by specifying one point in the plane and a normal vector.

If you want b), you need to define the mesh with a mesh data structure. Basically this is a list of coordinates and a list of triangular faces, where each face is defined by a set of 3 corner numbers . See here for an example. See here to learn how to generate 2D and 3D meshes in Matlab.

If you can provide an image that is like what you want, that would probably help.

Mad Gano 2022-7-5

thank you william I appreciate your support

William Rose 2022-7-5

@Mad Gano, you are welome. Good luck with your work.

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Answer 2

Pooja Kumari 2022-6-28

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在 MATLAB Online 中打开

Dear Mad Gano,

It is my understanding that you want to plot the given table in 3D using surf function and the values X,Y,Z have to be interpreted with respect to balloon size.

surf(X,Y,Z,C) creates a 3-D surface plot with x-y plane defined by X and Y and C taken surface color only.

You can only plot 3D graph using surf with three parameters at a time. So, if you want to plot your data with respect to balloon size.

%with different combination of X,Y,Z with respect to %BalloonSize. 
surf(X,Y,BalloonSize)
surf(Y,Z,BalloonSize)
surf(Z,X, BalloonSize)

For more information on surf function, you can follow the provided documentation below:

https://in.mathworks.com/help/matlab/ref/surf.html

For more information on jet function, follow the below provided link:

https://in.mathworks.com/help/matlab/ref/jet.html#:~:text=c%20%3D%20jet%20returns%20the%20jet,intensities%20for%20a%20specific%20color.

Sincerely,

Pooja Kumari

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How to plot 3D using a table

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