Dimension/Depth/Space/Scale

This image from "Numbers in Graphic Design" a book put together by Roger Fawcett-Tang to show different innovative ways of information design is a good example of how depth is used in graphic design. This design shows different figures all at different distances.  

The first use of Depth Perception elements is the use of overlap. In the first figure, the number 8 is overlapping the statue making it appear to be closer and bigger, giving it more of an importance than the statue. The same goes for the second figure in which the number 10 is overlapping the man. 

The second element used is relative size. The figure that appears to be in back of the rest is the number 0 which is scaled a lot smaller than the other two figures. Because of its size, we assume that it is farther away.

The third element is relative height. This relates to relative size because once again the 0 appears farther away since it is positioned higher up in the design. The 8, being the lowest, appears closer.