Guidance-based Two-Dimensional Haptic Contour Rendering for Accessible Photography

Abstract

Touching the faces of loved ones on a photograph can be a strong means to invoke associated pleasant memories to visually-impaired users, as seeing is to sighted users. Inspired by this long-term goal of multimodal accessible photography, we present in this paper a two-dimensional contour rendering algorithm based on haptic guidance using force feedback for tactile graphics. We begin with a basic algorithm for one contour and find its optimal guidance parameters by a user study. This basic algorithm is then applied to rendering geometric primitives, and its perceptual performance is evaluated by a shape identification experiment. We extend the basic algorithm to cover multiple contours and apply it to rendering portrait photographs. Major facial features are extracted from photographs, and their contours are rendered by our algorithms. It is demonstrated that users can accurately recognize emotional expressions on the faces, suggesting the high potential of our approach for enhancing accessible photography.