Accessing Subregions of Volume Data :: Volume Visualization Techniques (3-D Visualization)

3-D Visualization

Accessing Subregions of Volume Data

The subvolume function provides a simple way to access subregions of a volume data set. subvolume enables you to select regions of interest based on limits rather than using the colon operator to index into the 3-D arrays that define volumes. Consider the following two approaches to creating the data for a subvolume -- indexing with the colon operator and using subvolume.

Indexing with the Colon Operator

When you index the arrays, you work with values that specify the elements in each dimension of the array.

load wind
xsub = x(1:10,20:30,1:7);
ysub = y(1:10,20:30,1:7);
zsub = z(1:10,20:30,1:7);
usub = u(1:10,20:30,1:7);
vsub = v(1:10,20:30,1:7);
wsub = w(1:10,20:30,1:7);

Using the subvolume Function

subvolume enables you to use coordinate values that you can read from the axes. For example,

lims = [100.64 116.67 17.25 28.75 -0.02 6.86];
[xsub,ysub,zsub,usub,vsub,wsub] = subvolume(x,y,z,u,v,w,lims);

You can then use the subvolume data as inputs to any function requiring vector volume data.

Specifying Starting Points for Stream Plots Stream Line Plots of Vector Data