`reducevolume`

Keeps every n-th sample of 3-D volume data along each direction.

Syntax

Vr = reducevolume(V, R)

Keeps every R-th element along each of the three dimensions.

Vr = reducevolume(V, [Rx Ry Rz])

Uses a different step for each dimension.

[Xr, Yr, Zr, Vr] = reducevolume(X, Y, Z, V, R)

Also reduces the coordinate arrays.

Description

The operation picks the elements 1:R:end along each direction, so a step of 2 leaves about one eighth of the data. It speeds up slices, isosurfaces and other volume plots of big arrays. Note that the x direction corresponds to the second array dimension, as in meshgrid, so [Rx Ry Rz] is applied to dimensions 2, 1 and 3.

Input arguments

V: 3-D array of volume data.
R: Step: scalar, or three values [Rx Ry Rz] for the x, y and z directions.

Output arguments

Vr: Reduced volume.

Example

Subsample a volume

V = reshape(1:64, 4, 4, 4);
size(reducevolume(V, 2))
size(reducevolume(V, [2 2 1]))

Output

ans = 1×3

     2     2     2
ans = 1×3

     2     2     4

reducevolume