We address the topic of “pictorial depth” in cases of pictures that are unlike
photographic renderings. The most basic measure of “depth” is no doubt that of
depth order. We establish depth order through the pairwise
depth-comparison method, involving all pairs from a set of 49 fiducial points.
The pictorial space for this study was evoked by a capriccio (imaginary
landscape) by Francesco Guardi (1712–1793). In such a drawing pictorial space is
suggested by the artist through a small set of conventional depth cues. As a
result typical Western observers tend to agree largely in their visual awareness
when looking at such art. We rank depths for locations that are not on a single
surface and far apart in pictorial space. We find that observers resolve about
40 distinct depth layers and agree largely in this. From a previous experiment
we have metrical data for the same observers. The rank correlations between the
results are high. Perhaps surprisingly, we find no correlation between the
number of distinct depth layers and the total metrical depth range. Thus, the
relation between subjective magnitude and discrimination threshold fails to hold
for pictorial depth.