1. Piero della Francesca (ca. 1412– 1492) was a mathematician as well as an authority on linear perspective. He developed the distance method, shown here, for defining the dimensions of a tiled surface painted in perspective.
2. Charles Wheatstone (1802 – 1875) invented the stereoscope in the early 1830s and published his account of it in 1838. It consisted of two mirrors, each at 45° to the line of sight, so that slightly different drawings (with horizontal disparities) could be placed on the side panels. A single object (like the truncated pyramid) would be seen in depth.
3. Diagrams of viewing a small sphere with two eyes taken from Leonardo’s Notebooks. These have been reproduced in ref 4. When the sphere has a diameter smaller than the interocular separation then the whole of the background can be seen when two eyes are used.
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D&A WINTER 2008 Issue 07
4. Leon Battista Alberti (1404– 1472) formalised the principles of linear perspective in his book On painting published in 1435. He also suggested a method of capturing visual angles by looking at a scene with a fixed eye through a window: the contours can be traced on the glass.