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.