What do pictorial drawings have that can someone visualize objects?

a.
an x axis and a y axis
b.
depth
c.
several different types of lines
d.
a plane

To create an illustration of perspective, this artist did all of the following except 1) show clear orthogonal lines 2) have an implied vanishing point 3) distort proportion to keep the background and foreground the same size 4) include value changes between the foreground and background i was thinking maybe 1