Figure 28.

Pictorial configurations projected in the ground plan for observers (a) FA and (b) AD. These observers are very different, observer FA yielding remarkably shallow depth, observer AD ample pictorial depth. Yet both observers (as all the others) show very much the same effect. The overall best-fitting plane rotates in the direction of the picture plane, though not by ±45° but by rather less. All measures are in terms of pixels; blue denotes ‘clockwise’, red denotes ‘anticlockwise’, white denotes ‘frontal’.