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Slice and streamslice along diagonal

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djr
djr on 2 May 2020
Commented: Ameer Hamza on 3 May 2020
Hello,
I have X,Y,Z,U,V,W 3D arrays of the size 101x201x4. I plotted slice and streamslie in the x-z plane along y = -3 as shown in the attached figure (red line). The code is:
[X,Y,Z] = meshgrid(-4:0.05:6,-5:0.05:0,1:4);
% Plot streamlines for the given cross-section
ssh = streamslice(X,Y,Z,U,V,W,[],-3,[]);
set(ssh,'Color',[0 0 0],'LineWidth',2)
hold on
view(0,0)
% Plot volumetirc slice
Vel = sqrt(U.^2+V.^2+W.^2)
sh = slice(X,Y,Z,Vel,[],-3,[]);
colormap jet
set(sh,'EdgeColor','none',...
'FaceColor','interp',...
'FaceAlpha','interp');
alpha('color');
% c = colorbar('Location','eastoutside');
view(0,0)
zlim([0.5,4]); zl = zlim; zticks([1,2,3,4])
How can I plot the horizontal vs. z direction along the green line in the attached figure? That is, how to specify planes that are not at constant x,y or z?
Attahed is also a plot of what I would like in the diagonal direction, but I made it at y = -3 (red line in Slice.png)
Thank you,
djr

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Accepted Answer

darova
darova on 2 May 2020
Try this simple example
[x,y,z,v] = flow;
[Z,Y] = meshgrid(-3:0.5:3);
X = 3+(Z.^2+Y.^2)/5;
slice(x,y,z,v,X,Y,Z)
hold on
slice(x,y,z,v,[1 9],2,-2)
hold off
axis vis3d equal

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Ameer Hamza
Ameer Hamza on 2 May 2020
I suggest darova to add this comment as a separate answer so that djr can accept that. This code uses clever tricks and correctly solves the issue posed in the question.
djr
djr on 3 May 2020
I agree, I would be happy to do that. Should I post a new question separately or we can somehow do it here?
Ameer Hamza
Ameer Hamza on 3 May 2020
You can do it here. First unaccept my answer and then accept darova’s answer. Even accepting darova’s current answer will make it easy for anyone coming to this page to find a solution. Alternatively, if darova posted a new answer later, you can accept that too.

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More Answers (1)

Ameer Hamza
Ameer Hamza on 2 May 2020
Edited: Ameer Hamza on 2 May 2020
See this example, on how to create an arbitrary surface for the slice function: https://www.mathworks.com/help/releases/R2020a/matlab/ref/slice.html#mw_e9ea56fc-b860-4fbe-99d5-6c3e4725132f
You will need to do something like this. Suppose the equation of the green line is z=2*x (assuming x-axis is the horizontal axis)
x_range = -1:0.1:1;
y_range = -5:0.1:1;
[X_grid, Y_frid] = meshgrid(x_range, y_range);
Z = 2*x;
slice(X,Y,Z,V,X_grid,y_grid,Z)

  3 Comments

djr
djr on 2 May 2020
I also found this example (http://www.ece.northwestern.edu/local-apps/matlabhelp/techdoc/ref/slice.html), but I can't make it work for my data. It uses
surface
and
rotate
but there are some problems. When I pass (xd,yd,zd) to streamslice (not slice), then my Matlab (2018b) freezes. For some reason it takes way more time to do streamslice than slice.
Ameer Hamza
Ameer Hamza on 2 May 2020
It seems from the documentation of streamslice function that it might not be possible to create it along a specific plane. It just creates it parallel to the coordinate planes.
Try this simple example. I used a small grid to illsutrate the idea.
load wind
[xg, yg] = meshgrid(80:5:90, 20:2:25);
zg = 2*xg+yg;
streamslice(x,y,z,u,v,w,xg,yg,zg)
view(3)
djr
djr on 2 May 2020
Thanks a lot! Indeed it seems that the streamslice is not capable of handling a specific plane. That's a pity.
Cheers,
djr

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