Surface computing  Surface computing is the use of a specialized computer GUI in which traditional GUI elements are replaced by intuitive, everyday objects. Instead of a keyboard and mouse, the user interacts with a surface. Typically the surface is a touch-sensitive screen, though other surface types like non-flat three-dimensional objects have been implemented as well. It has been said that this more closely replicates the familiar hands-on experience of everyday object manipulation. Early work in this area was done at the University of Toronto, Alias Research, and MIT. Surface work has included customized solutions from vendors such as LM3LABS or GestureTek, Applied Minds for Northrop Grumman. Major computer vendor platforms are in various stages of release: the iTable by PQLabs, Linux MPX, the Ideum MT-50, interactive bar by spinTOUCH, and Microsoft PixelSense (formerly known as Microsoft Surface). Surface computing employs the use of two broad categories of surface types, flat and non-flat. The distinction is made not only due to the physical dimensions of the surfaces, but also the methods of interaction. Flat surface types refer to two-dimensional surfaces such as tabletops. This is the most common form of surface computing in the commercial space as seen by products like Microsoft's PixelSense and iTable. The aforementioned commercial products utilize a multi-touch LCD screen as a display, but other implementations use projectors. Part of the appeal of two-dimensional surface computing is the ease and reliability of interaction. Since the advent of tablet computing, a set of intuitive gestural interactions have been developed to complement two-dimensional surfaces. However, the two-dimensional plane limits the range of interactions a user is able to perform. Furthermore, interactions are only detected when making direct contact with the surface. In order to afford the user a wider range of interaction, research has been done to augment the interaction schemes for two-dimensional surfaces. This research involves using the space above the screen as another dimension for interaction, so, for example, the height of a user's hands above the surface becomes a meaningful distinction for interaction. This particular system would qualify as a hybrid that uses a flat surface, but a three-dimensional space for interaction. While most work with surface computing has been done with flat surfaces, non-flat surfaces have become an interest with researchers. The eventual goal of surface computing itself is tied to the notion of ubiquitous computing "where everyday surfaces in our environment are made interactive". These everyday surfaces are often non-flat, so researchers have begun exploring curved and three-dimensional modes.