Ben's escape in comic book picture 10 depends on a whole row of tree-trunks flowing into the background around them, along a fault line running horizontally across the scene. That breaks a rule that we take utterly for granted in everyday vision, but that greatly simplifies the task of the brain in making sense of the visual world: the outlines of objects form closed shapes - closed loops of outline, however wiggly the loops.
Look for example at the scene to the left. It records a spiritualist seance about a hundred years ago, and the blind-fold medium is making the table rise up, or levitate, (whether by spiritual means or trickery is not our problem just now). Below the photo, a selection of objects are isolated from it, to show that they are all made up of closed loops. It can take several loops to make up one object, if there are things in front of it, like the table here. Or the loops can have holes within them, like the back of the bent-wood chair here. Parts of loops can disappear into darkness too, or be cut of by the edge of the field of view. But in good illumination, objects never, ever, present outlines that open into the background. That might sound trivially obvious - but it can happen in the graphic world, as in the fork shown below to the left, and in the figure on the Opticaloctopus home-page, as well as in the trees in comic book picture 10.
You can construct the effect yourself with any scene presenting a row of elongated, separated shapes - of trees, limbs, pipes, columns. It is a good idea to include some well-behaved background detail, like the clouds in comic book picture 10, running at right angles to the lengths of the transforming row of objects, either side of the fault line across them.
& Comic Book Picture 10, Ben in the Trees
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Ben's escape in comic book picture 10 depends on a whole row of tree-trunks flowing into the background around them, along a fault line running horizontally across the scene. That breaks a rule that we take utterly for granted in everyday vision, but that greatly simplifies the task of the brain in making sense of the visual world: the outlines of objects form closed shapes - closed loops of outline, however wiggly the loops.
Look for example at the scene to the left. It records a spiritualist seance about a hundred years ago, and the blind-fold medium is making the table rise up, or levitate, (whether by spiritual means or trickery is not our problem just now). Below the photo, a selection of objects are isolated from it, to show that they are all made up of closed loops. It can take several loops to make up one object, if there are things in front of it, like the table here. Or the loops can have holes within them, like the back of the bent-wood chair here. Parts of loops can disappear into darkness too, or be cut of by the edge of the field of view. But in good illumination, objects never, ever, present outlines that open into the background. That might sound trivially obvious - but it can happen in the graphic world, as in the fork shown below to the left, and in the figure on the Opticaloctopus home-page, as well as in the trees in comic book picture 10.
There are numerous picture puzzles of this kind in psychologist Roger Shepard's wonderful book Mind Sights, (W.H.Freeman and co., New York, 1990). www.amazon.com/Mind-Sights-Illusions-Ambiguities-Anomalies/dp/0716721333
You can construct the effect yourself with any scene presenting a row of elongated, separated shapes - of trees, limbs, pipes, columns. It is a good idea to include some well-behaved background detail, like the clouds in comic book picture 10, running at right angles to the lengths of the transforming row of objects, either side of the fault line across them.