Tactile Graphics Rendering Using Three Laterotactile Drawing Primitives

This paper presents preliminary work towards the development and evaluation of a practical refreshable tactile graphics system for the display of tactile maps, diagrams and graphs for people with visual impairments. Refreshable tactile graphics were dynamically produced by laterally deforming the skin of a finger using the STReSS² tactile display. Tactile features were displayed over an 11x6 cm virtual surface by controlling the tactile sensations produced by the fingerpad-sized tactile display as it was moved on a planar carrier. Three tactile rendering methods were used to respectively produce virtual gratings, dots and vibrating patterns. These tactile features were used alone or in combination to display shapes and textures. The ability of the system to produce tactile graphics elements was evaluated in five experiments, each conducted with 10 sighted subjects. The first four evaluated the perception of simple shapes, grating orientations, and grating spatial frequencies. The fifth experiment combined these elements and showed that tactile icons composed of both vibrating contours and grated textures can be identified. The fifth experiment was repeated with 6 visually impaired subjects with results suggesting that similar performance should be expected from that user group.