MATLAB - quiver3

Create 3-D Quiver Plot

Load sample data that represents air currents over North America. For this example, select a subset of the data.

  load wind
X = x(5:10,20:25,6:10);
Y = y(5:10,20:25,6:10);
Z = z(5:10,20:25,6:10);
U = u(5:10,20:25,6:10);
V = v(5:10,20:25,6:10);
W = w(5:10,20:25,6:10);

Create a 3-D quiver plot of the subset you selected. The vectors X, Y, and Z represent the location of the base of each arrow, and U, V, and W represent the directional components of each arrow. By default, the quiver3 function shortens the arrows so they do not overlap. Call axis equal to use equal data unit lengths along each axis. This makes the arrows point in the correct direction.

  quiver3(X,Y,Z,U,V,W)
axis equal
fig2plotly()

• Plot
• SSIM

Disable Automatic Scaling

By default, the quiver3 function shortens arrows so they do not overlap. To disable automatic scaling so that arrow lengths are determined entirely by U, V, and W, set the scale argument to 0.

For example, first return the x-, y-, and z-coordinates of a unit sphere with 10-by-10 faces. Calculate the directional components of its surface normals using the surfnorm function. Then, create a 3-D quiver plot with no automatic scaling.

  [X,Y,Z] = sphere(10);
[U,V,W] = surfnorm(X,Y,Z);
quiver3(X,Y,Z,U,V,W,0)
axis equal
fig2plotly()

• Plot
• SSIM

For comparison, create the plot with automatic scaling. Note that the arrows are shorter and do not overlap.

  figure
quiver3(X,Y,Z,U,V,W)
axis equal
fig2plotly()

• Plot
• SSIM

Plot Vectors Normal to Surface

Plot vectors that are normal to the surface defined by the function z=xe-x2-y2. Use the quiver3 function to plot the vectors and the surf function to plot the surface.

First, create a grid of x- and y-values that are equally spaced. Use them to calculate z. Then, find the normal vectors.

  [X,Y] = meshgrid(-2:0.25:2,-1:0.2:1);
Z = X.*exp(-X.^2 - Y.^2);
[U,V,W] = surfnorm(X,Y,Z);
fig2plotly()

Display the vectors as a 3-D quiver plot. Then, display the surface in the same axes. Adjust the display so that the vectors appear normal to the surface by calling axis equal.

  quiver3(X,Y,Z,U,V,W)
hold on
surf(X,Y,Z)
axis equal
fig2plotly()

• Plot
• SSIM

Specify Arrow Color

Create a 3-D quiver plot and specify a color for the arrows.

For example, first return the x-, y-, and z- coordinates of a surface. Calculate the directional components of its surface normals using the surfnorm function.

  [X,Y] = meshgrid(-pi/2:pi/8:pi/2,-pi/2:pi/8:pi/2);
Z = sin(X) + cos(Y);
[U,V,W] = surfnorm(Z);

Then, create a 3-D quiver plot with red arrows.

  quiver3(X,Y,Z,U,V,W,'r')
axis equal
fig2plotly()

• Plot
• SSIM

Specify Axes for 3-D Quiver Plot

Starting in R2019b, you can display a tiling of plots using the tiledlayout and nexttile functions. Call the tiledlayout function to create a 1-by-2 tiled chart layout. Call the nexttile function to create an axes object and return the object as ax1. Create the left plot by passing ax1 to the quiver3 function. Add a title to the plot by passing the axes to the title function. Repeat the process to create the right plot.

  [X,Y] = meshgrid(-2:0.25:0,-2:0.25:0);
Z1 = -0.5*(X.^2 + Y.^2);
[U1,V1,W1] = surfnorm(Z1);
Z2 = -X.*Y;
[U2,V2,W2] = surfnorm(Z2);

tiledlayout(1,2)

% Left plot
ax1 = nexttile;
quiver3(ax1,X,Y,Z1,U1,V1,W1)
axis equal
title(ax1,'Left Plot')

% Right plot
ax2 = nexttile;
quiver3(ax2,X,Y,Z2,U2,V2,W2)
axis equal
title(ax2,'Right Plot')
fig2plotly()

• Plot
• SSIM

Modify 3-D Quiver Plot After Creation

Create a 3-D quiver plot and return the quiver object. Then, remove the arrowheads and add dot markers at the base of each arrow.

  [X,Y] = meshgrid(-3:0.5:3,-3:0.5:3);
Z = 0.2*(Y.^2 - X.^2);
[U,V,W] = surfnorm(Z);

q = quiver3(X,Y,Z,U,V,W);
axis equal
q.ShowArrowHead = 'off';
q.Marker = '.';
fig2plotly()

• Plot
• SSIM