US Patent 7715662 Method of generating interface surface having rotationally symmetric coded data

A method of generating an interface surface is provided in which machine-readable coded data is generated to be arranged in accordance with a layout having n-fold rotational symmetry about a center of rotation, where n is at least two, the layout including n identical sub-layouts rotated 1/n revolutions apart about the center of rotation, each sub-layout defining the position of data elements, and including rotation-indicating data that distinguishes that sub-layout from at least one other sub-layout, and the coded data is printed onto a surface to generate an interface surface.