This optical illusion is an effect of perspective. The temple isn't as it appears: the four columns are not actually vertical. Instead, they are tilted away from you. The point of view of the picture has been carefully chosen to make the columns "match up" and seem to connect with the pediment.
The illusion is hard to detect at first because you are only given one 2-dimensional view of the temple. Like a camera or a single eye, this view "flattens" the perspective and fails to give you any information about depth --- information that would reveal the true shape of the temple.
To reveal the illusion, play the QuickTime movie below to see the temple rotated 360 degrees. Or choose the QTVR version(Quick Time virtual reality) and rotate the temple yourself! (You will need the free Apple QuickTime 3 plugin to view the movies.)
This exhibit was created in cooperation with the Explor@dome in Paris.
[ Version Française ]