How to obtain a section from a surf plot

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Ricardo Duarte 2021-6-30

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https://ww2.mathworks.cn/matlabcentral/answers/868998-how-to-obtain-a-section-from-a-surf-plot

评论： Ricardo Duarte 2021-7-1

采纳的回答： KSSV

Dear all,

I have a surface plot that represents the bathymetry of a given surface:

x=longitute;

y=latitude;

z=depth;

Now, I want to obtain a section that cuts this surface at the latitude (37.9º) in order to obtain something like the following figure:

How can I do this?

Thanks in advance.

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DGM 2021-6-30

编辑：DGM 2021-6-30

在 MATLAB Online 中打开

The example image isn't a section. It simply appears to be the same surface from a 2D view, like

shading flat % get rid of edges
view([0 -1 0]) % set 2D view looking toward +y

Either that, or it represents some sort of difference information.

If you actually want a section, it will just be a line. If the query point where you want to make the section belongs to the x,y points you're using, then all you have to do is extract the corresponding vector from the Z data. If it lies between the plotted points, then you'll have to interpolate.

Ricardo Duarte 2021-7-1

Yes you are rigth, the second image is not a section.

I really want a section that will be represented by a single line. The problem is that i don't know how to extract that data.

Thanks

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Answer 1

KSSV 2021-7-1

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https://ww2.mathworks.cn/matlabcentral/answers/868998-how-to-obtain-a-section-from-a-surf-plot#answer_737408

在 MATLAB Online 中打开

Check this demo example, may be useful.

[X,Y,Z] = peaks(100) ; 
surf(X,Y,Z)
xi = unique(X(:)) ; 
val = 0; dx = 10^-3 ; w = 10 ;
yi = linspace(val-dx,val+dx,w) ;
[Xi,Yi] = meshgrid(xi,yi) ; 
Zi = interp2(X,Y,Z,Xi,Yi) ;
surf(Xi,Yi,Zi)

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DGM 2021-7-1

编辑：DGM 2021-7-1

在 MATLAB Online 中打开

Or instead of scatter3(), just

plot(xi,zi)

if you don't need the color mapping and want a plain 2D solid line.

or

h = surf([xi(:) xi(:)],[yi(:) yi(:)],[zi(:) zi(:)]);
set(h,'facecolor','none','edgecolor','interp');
set(h,'linewidth',3); % make it fat so it's easier to demonstrate
view([0 -1 0]); % only show 2-D view
colormap(parula);