The Pioneer 10 and 11 deep-space probes carry a plaque for the benefit of any aliens they might run into. On it is a line drawing of a man and a woman. Will it make any sense to its intended audience? Even if extraterrestrials notice the markings and recognize them as a picture, will they apprehend the 3-D figures?
Many of the artistic conventions we take for granted had to be invented, and they reflect a specific cultural (let alone planetary) context. The perspective view used on the Pioneer plaque is one example. It produces the illusion of depth by showing distant objects smaller than nearby ones and by ensuring that parallel lines converge on a vanishing point. Many software packages now automate these techniques and enable artists to create photorealistic images with relative ease.
Yet realism has not always been an ambition of artists. Although elements of perspective go at least as far back as Greek painter Agatharchus in the fifth century B.C., it became popular only with the Italian Renaissance. In early 15th-century Florence, architect Filippo Brunelleschi performed a public demonstration with mirrors (then a new technology) to show how faithfully his paintings depicted building facades. He inspired painters such as Donatello, Masaccio and Domenico di Bartolo (painting above); Leon Battista Alberti worked out the math. Their rigorous geometric constructions ensured that natural depth cues such as size, vertical position and tile patterns were mutually consistent for maximum verisimilitude.
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Learning to view a perspective drawing requires accepting and overlooking its limitations, such as its assumption of a single viewpoint. In computer graphics, perspective is well suited to first-person shooter games, but games such as SimCity that show a bird’s-eye view use a different technique, axonometric projection, elements of which go back to Chinese painters in the second century B.C. Not only should we wonder whether aliens will be able to decipher our drawings, we should also ask whether we would recognize alien artwork if we saw it.