The user wearing a head-mounted display sees a small hemisphere. The tactile feedback is provided with a shape display. Instead of rendering the small hemisphere (top), the shape display renders a larger hemisphere with higher resolution (bottom) that is mapped to the virtual shape by altering the user’s perception of scale and redirecting the finger.
We utilize visuo-haptic illusions to improve the perceived performance of encountered-type haptic devices, specifically shape displays, in virtual reality. Shape displays are matrices of actuated pins that travel vertically to render physical shapes; however, they have limitations such as low resolution, small display size, and low pin speed. To address these limitations, we employ illusions such as redirection, scaling, and retargeting that take advantage of the visual dominance effect, the idea that vision often dominates when senses conflict. Our evaluation of these techniques suggests that redirecting sloped lines with angles less than 40 degrees onto a horizontal line is an effective technique for increasing the perceived resolution of the display. Scaling up the virtual object onto the shape display by a factor less than 1.8x can also increase the perceived resolution. Finally, using vertical redirection a perceived 3x speed increase can be achieved.