3D Artists' Dazzling Display of Depth

Thousands of pedestrians in the real world, and millions of surfers on the Internet have been astonished by remarkable 3D drawings made by two talented pavement (sidewalk) artists, Kurt Wenner of the US and Julian Beever of the UK. It's almost impossible to believe their works are actually presented on a flat surface.

Kurt Wenner was born in Ann Arbor, Michigan, grew up in Santa Barbara, California, and by the time he was 17 was earning a living as a graphic artist. NASA later employed him as an advanced scientific space illustrator, creating conceptual paintings of future space projects and extra-terrestrial landscapes based on information from the Voyager spacecraft.

In 1982, he left NASA and sold his belongings to go to Italy. There, he studied the great masters and made drawings of classical sculptures in the museums. He brought 3-D (anamorphism) to the art of street painting, and was featured in a National Geographic Special in the early 1980s. Since then, he has attracted huge crowds of admirers watching him produce 3D masterpieces on sidewalks in the US, Canada, Japan, Mexico, Italy, Sweden and the Netherlands.

"They are fine examples of an art form known as anamorphism, in which the picture is distorted so that it assumes a normal appearance when viewed from a specific viewpoint," says Paolo Attivissimo from Italy. "This is a well-known technique, often employed in film and theatre production to create the illusion of depth."

Julian Beever, based in Britain, has made pavement drawings for more than 10 years. He has worked in the UK, Belgium, France, the Netherlands, Germany, the USA and Australia, according to his website. He specialises in pavement drawings, wall murals and traditional paintings.

Vaughan Bell, of Cardiff (Wales) University's School of Psychology, says:

Julian Beever is a street artist who takes advantage of the way the brain understands the world to create some amazing artwork. The brain works out our 3D experience of the world from the 2D light patterns that fall onto our retina at the back of the eye.

This process takes advantage of many of our implicit assumptions of the world, such as the fact that textures will fade as they go farther away, parallel lines will tend to converge in the distance and that objects will seem larger the closer they are.

Julian Beever's art uses a knowledge of these processes, so when seen from a certain angle, the pictures fool the visual system's inbuilt processes to produce a false sense of depth.

When seen from an alternative angle, the illusion breaks down, and it's possible to see how the artwork was created.

Turning to other visual illusions, Michael Bach's website in Germany claims to be attracting two million hits a day. It shows rotating circles and other colorful patterns which make you dizzy when you look at them.

"These pages demonstrate visual phenomena, called optical illusions or visual illusions." he says. "The latter is more appropriate, because most effects have their basis in the visual pathway, not in the optics of the eye...

"Most visitors of this site are not vision scientists, so you might find the explanatory attempts too highbrow. That is not on purpose, but vision research just is not trivial, like any science. So, if the explanation sounds like rubbish, simply enjoy the phenomenon ."