MATLAB: Confusion in cat command

Question

I am reading matlab online documentation for fliplr command and there and i came across a command 'cat'

It is used for concatenation.

First argument of cat command specifes dimension along which concatenation. example if first argument is 1 ,matrices are concatenaated along coulmns and if first argumetn is 2, matrices will be concatenated along rows. But what if first argument is 3 as in this scenario

I am confused how it is acting as shown in current scenario in attached photo. What will be contents of A ? and what is the meaning of highligted lines?

Answer 1

3 means the 2-D arrays are being stacked along the 3rd dimension. To visualize, imagine that the arrays are gray scale images in the x-y plane. Now you use cat() to stack them vertically along the third, Z, dimension. See image below, and attached demo script.

The 3-D image above would represent a color image.

Another case could be where you have lots of images, like slices from a CT or MRI scan. These images, stacked along the 3rd dimension would represent a volumetric images.

If the number were 4, then it could mean that you're stacking 3-D (color) images along the 4th dimension (representing time) to create a movie.

Does that explain it sufficiently to you?