Draw 3D plot from 2D plot with discrete data points

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autumn 2021-7-19

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https://ww2.mathworks.cn/matlabcentral/answers/881958-draw-3d-plot-from-2d-plot-with-discrete-data-points

评论： Star Strider 2021-7-23

采纳的回答： Star Strider

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Hi All,

I am trying to draw 3D plot from a 2D line graph (in x/z-axis).

I have discrete data points in x and z-axis like below graph. I want to roate it around z-axis. Therefore, I used 'surf'

Here is what I obtained so far.

filename = 'filename.xlsx'; 
  x(:,:)= xlsread(filename); 
  r = (x(4:49,12))'; z = (x(4:49,13))'; %% data from excel
 for i = 1:46;
 theta = linspace(0,2*pi,200); %% to rotate around z-axis 
 X = r(i)*cos(theta);
 Y = r(i)*sin(theta); 
 Z = z(i)*ones(length(Y), length(X));
 plot(X,Y); %% just for checking X and Y are on circles 
 surf(X,Y,Z); %% wanted to obtain a smooth mountain with an empty center. 
    if i < 46;
     hold on;
     i = i+1;
    end;
 end
 xlabel('x'); ylabel('y');zlabel('z');
 hold off
 shading interp
 colorbar 

and this is the result..

The profile has to be very smooth, no sharp edges on the boundary. However, it has four edges. Also, when x<450, there is be no data points in z-axis.. but it shows very flat top surface (yellow). I think I need to assign z-values at the correct x and y coordinates. However, I am not sure how to fix this.

Please help me to resolve this issue.

Thanks a lot for your comments and time in advance!

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采纳的回答

Star Strider 2021-7-20

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https://ww2.mathworks.cn/matlabcentral/answers/881958-draw-3d-plot-from-2d-plot-with-discrete-data-points#answer_750208

在 MATLAB Online 中打开

Without the Excel file, I experimented to create an approsimately equal curve. I then used it as the radiuc argument to the cylinder fucntion to create the surf plot.

x = linspace(460, 700, 50);

z = 1E-194*exp(-0.025*x+460) + 1.5;

figure

plot(x, z)

title('Radius Curve')