Methods, systems, computer-readable media, and apparatuses for providing intuitive, functional, and convenient ways of enabling a user of a head-mounted display unit or another augmented reality enabled device to interact with various user interfaces and other features provided by such a unit or device are presented. In some embodiments, a computing device, such as a head-mounted display unit, may receive camera input of a scene. Subsequently, the computing device may identify at least one reference object in the scene, for example, based on detecting one or more rectangles in the received camera input. The computing device then may receive input that defines a surface segment relative to the at least one reference object. Thereafter, the computing device may render the surface segment.