Irises are commonly used to regulate depth of field and the amount of light that is exposed in aperture settings in camera lenses. This concept for a building's facade is "Composed of single aperture-modules with receptor (LDR - light dependent resistor) and actuator (servo-motor/iris), aperture acts like an autonomous skin, which is also capable of precise external control", explained Frédéric Eyl and Gunnar Green, the two students who created the technology.

Since the aperture has a variable opening diameter, it can change in order to regulate the surface when someone passes inside the building, thus transmitting the visual information to the outside of the building. "Each of the apertures in the array can be used to represent a pixel of an image" say the concept's developers.

The apertures in the grid alter their diameters correspondingly to the varying intensities of incoming light. They mimic a person's movement by opening and closing so that even different phases of a movement are captured and displayed. A prototype of the technology was built in 2005 and a visualization of the aperture can be seen here.

This intelligent surface has a "memory" mode capable of recalling images it captured during the day and displaying them in case no human activity is present at that time. If a person standing in front of the wall leaves, his displayed image fades out after a while. The time it takes for the image to fade out depends on the time that person spent there.

IN 2007 TFOT covered several other interactive surfaces such as interactive paper that is responsive to a human touch anda new kind of wallpaper that also serves as a light source, sensitive floor - an interactive video floor projection that reacts to the way people walk on it. Back in 2006 TFOT covered the World's First Concrete Screen developed by students togther with the Danish concrete manufacturer Dalton Beton.

More information on the Aperture can be found here.