Figure 3 shows two crosses approaching the observer, as in Figure 1, but also rotating, as in Figure 2. The crosses are shown in a time-lapu illustration, as in Figure 1. As the crosses approach the observer they increase in angular subtense and the gaps between the crosses also increase in angular subtense. Figure 4 shows a field of dots rotating and decreasing in distance from the observer. Characteristically, when an entire field of dots decreases in distance from the observer the reason is that the observer is moving through a volume of dots, or towards a surface with a texture of dots.
Observers typically gd the impression that the vantage point is moving.
In this illustration, the dots are shown leaving trails, as in Figure 2. Figure 5 shows how points on a pair of circles physically move if they rotate around a fixed dot. The arrows show the directions of motions of points on the circles, and the lengths of the arrows show how fast the points are moving. Points near the central fisced dot move less. The longest arrow is attached to the point that is farthest from the centre of rotation.