Caption: "Comparison of the measured FitzGerald contraction of a cube versus its visual appearance as given by the Terrell-Penrose effect. The view is from the front of the cube at a distance four times the length of the cube's sides, three-quarters of the way from bottom to top, as projected onto a vertical screen (so that the vertical lines of the cube are initially parallel)." (Slightly edited.)
Features:
L(v)=L_0*sqrt(1-v**2/c**2) , where v is the observer's velocity relative an object, L(v) is the observer's observed length for the object along the direction of motion, and L_0 is the length along the direction of motion measured in rest frame of the object. L_0 is called the proper length in Relativityspeak.
If you correct for the differential time delay, then you get a true measurement of length and observe the FitzGerald contraction.
What you observe sans correction is a rotation, the Terrell-Penrose effect.
The Terrell-Penrose effect is illustrated by the right-hand side of the animation.