OH WELL, no one’s perfect. For centuries, Michelangelo’s sculpture
David has been held up as the ultimate in male physical beauty. But now a
laser scan of his face has revealed the truth: he squints.
“The gaze directions of his eyes actually diverge,” says computer scientist
Marc Levoy of Stanford University in California, who spent a sabbatical making
computerised images of Italian sculptures.
One of the project’s aims was to capture views that Michelangelo never
intended us to see. In David’s case, this includes the full-frontal
view of his face, which is usually hidden by his upraised left hand. Levoy is
convinced that Michelangelo did this on purpose.
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In the classic three-quarter view, the
5.2-metre-tall David is looking slightly off to his
left—eyeballing Goliath, before felling him with a slingshot. In left
profile he stares straight ahead like a portrait on a Roman coin. “It’s a
typical Michelangelo trick,” Levoy says. “He optimised each eye for its
appearance as seen from the side.”
These days you rarely see the left profile because you’d have to look through
the wall of the Galleria dell’Accademia in Florence. But it was in plain view at
the sculputure’s original site, which was outside the Palazzo Vecchio.
To create his images, Levoy shone a thin sheet of laser
light onto the statue and recorded the shape of the beam edge as it swept across
the surface. Repeated scans can be overlaid to generate an image that is
detailed enough to show chisel marks less than a millimetre across and tiny
cracks in the marble.
Levoy revealed David’s squint by hoisting the scanner onto a gantry
and pointing it straight at David’s face. But first he had to add an
extra metre to the gantry to compensate for an error in the Accademia’s
guidebook, which lists David as standing 14 feet (4.3 metres) tall plus
6 feet of pedestal.
“My initial response is that it’s very interesting,” says Peta Motture, a
Renaissance sculpture expert at the Victoria & Albert Museum in London,
which owns a cast of David. “He’s always been interpreted as looking
into the distance. I might need to go away and have another look at him.”
Levoy has now turned his attention to one of archaeology’s most enduring
puzzles, the Forma Urbis Romae, a giant map of ancient Rome carved onto
marble slabs around 200 AD. The map now lies in more than 1000 pieces waiting to
be reconstructed by hand. Levoy hopes that three-dimensional scans of the broken
edges can be used by a computer to help piece the jigsaw together.
“The broken surfaces give us strong three-dimensional cues for fitting the
pieces back together,” he says. Levoy is now developing the algorithms the
computer will use to fit the pieces together automatically.