Smith-Kettlewell Eye Research Institute
 Christopher W. Tyler
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  Introduction   |   One point   |   Construction lines   |   Construction method   |   Globes   |   Canaletto   |   Summary

Use of Construction Lines

In this bizarre double scene of St. Julian decapitating his parents in their bed, many construction lines have been inscribed into the surface of the wooden panel. Clearly, in this early Quattrocento painting, Masolino was taking great care with the geometry, but it is highly implausible that he set up the scene in an optical projection.

From all parts of the picture, all fourteen construction lines converge accurately to a single vanishing point. Although little recognized by art historians, this painting by Masolino is one of the two earliest in history to exhibit an accurate convergence of a three-dimensional geometry to a single vanishing point.

Other artists, such as Leonardo, provided good evidence for the use of a geometric approach to perspective construction. Clearly he was not using a camera obscura to derive these sketches of the camel and the prancing horses. These must represent his raw artistic talent. Other sketches by Leonardo amplify the point that optical projection is very different from photographs, in being unable to freeze the motion in a scene.


Leonardo da Vinci's perspective diagram for the 'Adoration of the Magi' (1481)

Leonardo da Vinci's sketch for the 'Battle of Alghiari' (1505)

Again, in Bellini's painting, the starting horse must have been drawn entirely from his observation and memory. He could neither have posed the horse nor captured its optical projection while is was moving. Again, Raphael's vivid prancing horse must have been drawn from memory, and the dragon must, of course, been entirely imaginary.


Giovanni Bellini, St. George Fighting the Dragon, (1474)

Raphael, St. George and the Dragon, (1505)

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