Larger Than Life
Artist Jorge Rodríguez-Gerada used the smallest materials, grains of sand, to create Expectation, a gargantuan portrait of Barack Obama spanning 2.5 acres of beachfront in Barcelona. The president’s likeness is imperceptible at human eye level, but from a bird’s-eye view the picture comes alive. Sandpainting—especially at a gigantic scale—is a form of pointillism, the technique used by painters such as Georges Seurat, Paul Signac and Vincent van Gogh, in which the juxtaposition of multiple individual points creates patterns and shades of color that become apparent only from afar. The illusion works as long as the image of every element (dot of paint, grain of sand) on the retina is roughly equal to the size of a photoreceptor. Our retina sees the world as a field of photoreceptor points of light, whether they were drawn that way or not, which makes viewing distance critical to our perception of texture. The fine details of wood grain and other textures are visible only up close, when they fall directly on our fovea, the central region of each of our retinas where photoreceptor density is highest. Our photoreceptors are unable to resolve the subtle differences in color or shape of an object when we step away, so the coarser features of the image dominate our perception instead.

Children Crossing
One practical application of anamorphic perspective is roadway writing. The abnormally elongated shape of warnings such as “children crossing” allows drivers to read them easily as they approach the text. British Columbia–based safety-awareness group Preventable has pushed this concept to the limit, hoping to change drivers’ attitudes in a guerrilla marketing campaign. The group’s 45-foot illusion, which portrays a young girl chasing a ball across a busy intersection, stayed for a week near a school in West Vancouver. When drivers approached the image, the girl’s shape started to form from about 50 feet away and remained three-dimensional for another 40 feet. You can see the video at www.preventable.ca/2010/09/shifting-attitudes-with-illusions.

This article was originally published with the title Urban Illusions.

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