Why an Atheist Thinks the Shroud of Turin is the Real Deal

The Importance of the Play of Light

In some cases the play of light is essential in artistic renderings. For instance, a picture of the earth floating in space requires the use of highlights and shading. Otherwise it simply looks like a flat disk. And those fake, seemingly raised push buttons on web pages that you seem to be able to push in by clicking on them with your mouse, are created by simple highlights and shading around rectangles. Interestingly, they reveal another illusion about three-dimensionality. We are conditioned, perhaps by the sun, to expect light from above. Those web buttons look raised because the light seems to strike the upper edges. As soon as the computer programmer (and that is who is ultimately responsible) puts shading on top and highlight on the bottom, the rectangles look like depressed buttons. It’s an illusion, but it tells us a great deal about how we perceive depth.