Game World!: How do you slice in Matlab?

Volumetric slice plot

Syntax

slice(V,sx,sy,sz)
slice(X,Y,Z,V,sx,sy,sz)
slice(V,XI,YI,ZI)
slice(X,Y,Z,V,XI,YI,ZI)
slice(...,'method')
slice(axes_handle,...)
h = slice(...)

Description

slice displays orthogonal slice planes through volumetric data.

slice(V,sx,sy,sz) draws slices along the x, y, z directions in the volume V at the points in the vectors sx, sy, and sz. V is an m-by-n-by-p volume array containing data values at the default location X = 1:n, Y = 1:m, Z = 1:p. Each element in the vectors sx, sy, and sz defines a slice plane in the x-, y-, or z-axis direction.

slice(X,Y,Z,V,sx,sy,sz) draws slices of the volume V. X, Y, and Z are three-dimensional arrays specifying the coordinates for V. X, Y, and Z must be monotonic and orthogonally spaced (as if produced by the function meshgrid). The color at each point is determined by 3-D interpolation into the volume V.

slice(V,XI,YI,ZI) draws data in the volume V for the slices defined by XI, YI, and ZI. XI, YI, and ZI are matrices that define a surface, and the volume is evaluated at the surface points. XI, YI, and ZI must all be the same size.

slice(X,Y,Z,V,XI,YI,ZI) draws slices through the volume V along the surface defined by the arrays XI, YI, ZI.

slice(...,'method') specifies the interpolation method. 'method' is 'linear', 'cubic', or 'nearest'.

linear specifies trilinear interpolation (the default).
cubic specifies tricubic interpolation.
nearest specifies nearest-neighbor interpolation.

slice(axes_handles,...) plots into the axes with handle axes_handle instead of the current axes object (gca).

h = slice(...) returns a vector of handles to surface graphics objects.

Remarks

The color drawn at each point is determined by interpolation into the volume V.

Examples

Visualize the function

over the range -2 x 2, -2 y 2, - 2 z 2:

[x,y,z] = meshgrid(-2:.2:2,-2:.25:2,-2:.16:2);
v = x.*exp(-x.^2-y.^2-z.^2);
xslice = [-1.2,.8,2]; yslice = 2; zslice = [-2,0];
slice(x,y,z,v,xslice,yslice,zslice)
colormap hsv

Slicing At Arbitrary Angles

You can also create slices that are oriented in arbitrary planes. To do this,

Create a slice surface in the domain of the volume (surf, linspace).
Orient this surface with respect to the axes (rotate).
Get the XData, YData, and ZData of the surface (get).
Use this data to draw the slice plane within the volume.

For example, these statements slice the volume in the first example with a rotated plane. Placing these commands within a for loop "passes" the plane through the volume along the z-axis.

for i = -2:.5:2
    hsp = surf(linspace(-2,2,20),linspace(-2,2,20),zeros(20)+i);
    rotate(hsp,[1,-1,1],30)
    xd = get(hsp,'XData');
    yd = get(hsp,'YData');
    zd = get(hsp,'ZData');
    delete(hsp)
    slice(x,y,z,v,[-2,2],2,-2) % Draw some volume boundaries
    hold on
    slice(x,y,z,v,xd,yd,zd)
    hold off
    axis tight
    view(-5,10)
    drawnow
end

The following picture illustrates three positions of the same slice surface as it passes through the volume.

Slicing with a Nonplanar Surface

You can slice the volume with any surface. This example probes the volume created in the previous example by passing a spherical slice surface through the volume.

[xsp,ysp,zsp] = sphere;
slice(x,y,z,v,[-2,2],2,-2)  % Draw some volume boundaries

for i = -3:.2:3
    hsp = surface(xsp+i,ysp,zsp);
    rotate(hsp,[1 0 0],90)
    xd = get(hsp,'XData');
    yd = get(hsp,'YData');
    zd = get(hsp,'ZData');
    delete(hsp)
    hold on
    hslicer = slice(x,y,z,v,xd,yd,zd);
    axis tight 
    xlim([-3,3])
    view(-10,35)
    drawnow
    delete(hslicer)
    hold off
end