Stream ribbons illustrate direction of flow, similar to stream lines, but can also
show rotation about the flow axis by twisting the ribbon-shaped flow line. The
streamribbon function enables you
to specify a twist angle (in radians) for each vertex in the stream ribbons.
When used in conjunction with the
streamribbon is useful for displaying the curl angular
velocity of a vector field. The following example illustrates this technique.
Load and select a region of interest in the
wind data set using
subvolume. Plotting the full data
set first can help you select a region of interest.
load wind lims = [100.64 116.67 17.25 28.75 -0.02 6.86]; [x,y,z,u,v,w] = subvolume(x,y,z,u,v,w,lims);
Calculate the curl angular velocity and the wind speed.
cav = curl(x,y,z,u,v,w); wind_speed = sqrt(u.^2 + v.^2 + w.^2);
stream3 calculates the
stream line vertices with a step size of
streamribbon scales the
width of the ribbon by a factor of
2 to enhance the
visibility of the twisting (which indicates curl angular velocity).
streamribbon returns the handles of the surface objects
it creates, which are then used to set the color to red
FaceColor), the color of the surface edges to light
EdgeColor), and slightly increase the brightness of
the ambient light reflected when lighting is applied
[sx sy sz] = meshgrid(110,20:5:30,1:5); verts = stream3(x,y,z,u,v,w,sx,sy,sz,.5); h = streamribbon(verts,x,y,z,cav,wind_speed,2); set(h,'FaceColor','r',... 'EdgeColor',[.7 .7 .7],... 'AmbientStrength',.6)
axis(volumebounds(x,y,z,wind_speed)) grid on view(3) camlight right;