Haptic rendering of photographs

Exploration of 2-D images is a challenging problem in computer haptics and research has primarily been focused on the exploration of restricted types of images, e.g., maps or mathematical curves. In contrast, this paper describes the design and implementation of a system for the haptic exploration of general photographs. We transform the photograph to a set of contours which are then rendered as three-dimensional grooves on a 2D image plane in the haptic workspace. Our haptic image explorer supports various user interactions including zooming and panning. Our major contribution is the support for browsing multiple levels-of-detail of the contour image in order to help users understand the image more readily. The levels-of-detail are derived from an object-level segmentation hierarchy of the source photograph. We also investigate if ambient encoding of the spatial surrounding of the haptic cursor in the image is beneficial during exploration. We briefly discuss a user study to evaluate the efficacy of multiple levels-of-detail and of ambient encoding of the spatial surrounding through textures.