when would i need an array of 3 or4 dimentions?

Question

Why would i need to form an array of more than 2 dimensions? What properties would i need?

Answer 1

These situations are often rather specialized, as most of the data people tend to work with is lower dimensional. But, consider 3D graphics, you'd need to track positions in all three dimensions before you perform the protection onto the screen. What if want the colors to vary by some function other than pure position? There's a 4D array.

Astronomy:
What about position (minimum of 2D), polarization (takes 4 values to define), 'colour' (which is often a mix of values fun different measurements) of a source? That's not even taking into account the potential for the source to vary in time.

These types of data do exist, but they're often then broken down and presented to a 2D format for clarity (humans grok that easier).