coneplot

Plot velocity vectors as cones in 3-D vector field

Syntax

coneplot(X,Y,Z,U,V,W,Cx,Cy,Cz)
coneplot(U,V,W,Cx,Cy,Cz)
coneplot(...,s)
coneplot(...,color)
coneplot(...,'quiver')
coneplot(...,'method')
coneplot(X,Y,Z,U,V,W,'nointerp')
coneplot(axes_handle,...)
h = coneplot(...)

Description

coneplot(X,Y,Z,U,V,W,Cx,Cy,Cz) plots velocity vectors as cones pointing in the direction of the velocity vector and having a length proportional to the magnitude of the velocity vector. X, Y, Z define the coordinates for the vector field. U, V, W define the vector field. These arrays must be the same size, monotonic, and represent a Cartesian, axis-aligned grid (such as the data produced by meshgrid). Cx, Cy, Cz define the location of the cones in the vector field. The section Specifying Starting Points for Stream Plots in Visualization Techniques provides more information on defining starting points.

coneplot(U,V,W,Cx,Cy,Cz) (omitting the X, Y, and Z arguments) assumes [X,Y,Z] = meshgrid(1:n,1:m,1:p), where [m,n,p]= size(U).

coneplot(...,s) automatically scales the cones to fit the graph and then stretches them by the scale factor s. If you do not specify a value for s, coneplot uses a value of 1. Use s = 0 to plot the cones without automatic scaling.

coneplot(...,color) interpolates the array color onto the vector field and then colors the cones according to the interpolated values. The size of the color array must be the same size as the U, V, W arrays. This option works only with cones (that is, not with the quiver option).

coneplot(...,'quiver') draws arrows instead of cones (see quiver3 for an illustration of a quiver plot).

coneplot(...,'method') specifies the interpolation method to use. method can be linear, cubic, or nearest. linear is the default. (See interp3 for a discussion of these interpolation methods.)

coneplot(X,Y,Z,U,V,W,'nointerp') does not interpolate the positions of the cones into the volume. The cones are drawn at positions defined by X, Y, Z and are oriented according to U, V, W. Arrays X, Y, Z, U, V, W must all be the same size.

coneplot(axes_handle,...) plots into the axes with the handle axes_handle instead of into the current axes (gca).

h = coneplot(...) returns the handle to the patch object used to draw the cones.

coneplot automatically scales the cones to fit the graph, while keeping them in proportion to the respective velocity vectors.

Examples

expand all

3-D Cone Plot

Plot velocity vector cones for vector volume data representing motion of air through a rectangular region of space.

Load the data. The wind data set contains the arrays u, v, and w that specify the vector components and the arrays x, y, and z that specify the coordinates.

load wind

Establish the range of the data to place the slice planes and to specify where you want the cone plots.

xmin = min(x(:));
xmax = max(x(:));
ymin = min(y(:));
ymax = max(y(:));
zmin = min(z(:));

Define where to plot the cones. Select the full range in x and y and select the range 3 to 15 in z.

xrange = linspace(xmin,xmax,8);
yrange = linspace(ymin,ymax,8);
zrange = 3:4:15;
[cx,cy,cz] = meshgrid(xrange,yrange,zrange);

Plot the cones and set the scale factor to 5 to make the cones larger than the default size.

figure
hcone = coneplot(x,y,z,u,v,w,cx,cy,cz,5);

Set the cone colors.

hcone.FaceColor = 'red';
hcone.EdgeColor = 'none';

Calculate the magnitude of the vector field (which represents wind speed) to generate scalar data for the slice command.

hold on
wind_speed = sqrt(u.^2 + v.^2 + w.^2);

Create slice planes along the x-axis at xmin and xmax, along the y-axis at ymax, and along the z-axis at zmin. Specify interpolated face color so the slice coloring indicates wind speed, and do not draw edges.

hsurfaces = slice(x,y,z,wind_speed,[xmin,xmax],ymax,zmin);
set(hsurfaces,'FaceColor','interp','EdgeColor','none')
hold off

Change the axes view and set the data aspect ratio.

view(30,40)
daspect([2,2,1])

Add a light source to the right of the camera and use Gouraud lighting to give the cones and slice planes a smooth, three-dimensional appearance.

camlight right
lighting gouraud
set(hsurfaces,'AmbientStrength',0.6)
hcone.DiffuseStrength = 0.8;

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