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Quiver plot arrows hidden by surface plot?

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Mark Lepage
Mark Lepage on 24 Apr 2019
Commented: Star Strider on 25 Apr 2019
Hello all,
I am creating a surface plot, and plotting on top of this a quiver plot. Everything works great, however where I have large "z" values on my surface plot, the quiver arrows are being hidden by the graph.
Any ideas how to solve this? I have attached an image of my problem, look at the yellow boxes, where the quiver arrows are hidden.

Accepted Answer

Star Strider
Star Strider on 24 Apr 2019
I was considering something like this:
x = linspace(-pi, pi, 20);
h = x(2)-x(1);
[X,Y] = ndgrid(x);
Z = sin(X) .* cos(Y);
[U,V] = gradient(Z,h,h);
W = zeros(size(U));
surf(X, Y, Z)
hold on
quiver3(X,Y,Z, U,V,W, 0.7, 'r')
hold off
grid on
view(0, 90)
All the arrows are visible because they all plot with respect to ‘Z’. The ‘W’ matrix simply makes them plot in a plane. (I made them red so they’re more visible.)
Star Strider
Star Strider on 24 Apr 2019
My pleasure.
The Z-offset is simply the zeros ‘W’ matrix that effectively plots the arrows on top of the surf plot. Instead of 3D quiver arrows, the ‘W’ matrix creates the arrows as a 2D plane, however with their origins on the ‘Z’ values of the surf plot. You can see this by using the GUI (‘Tools’ -> ‘Rotate 3D’) or the view function to rotate the plot to see the arrows with respect to the ‘Z’ surface elevation. They all plot above it, regardless of where they originate.
That’s probably as well as I can explain it.

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More Answers (1)

Thomas Rosin
Thomas Rosin on 24 Apr 2019
I don't think there are hidden, I just think your arrow size is too small.
The tip of the arrow scale with its length but it's a parameters you can set on the quiver function.
Star Strider
Star Strider on 25 Apr 2019
@Mark Lepage —
As always, my pleasure.

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