Redirected walking techniques can enhance the immersion and visual-vestibular comfort of virtual reality (VR) navigation, but are often limited by the size, shape, and content of the physical environments. We propose a redirected walking technique that can apply to small physical environments with static or dynamic obstacles. Via a head- and eye-tracking VR headset, our method detects saccadic suppression and redirects the users during the resulting temporary blindness. Our dynamic path planning runs in real-time on a GPU, and thus can avoid static and dynamic obstacles, including walls, furniture, and other VR users sharing the same physical space. To further enhance saccadic redirection, we propose subtle gaze direction methods tailored for VR perception. We demonstrate that saccades can significantly increase the rotation gains during redirection without introducing visual distortions or simulator sickness. This allows our method to apply to large open virtual spaces and small physical environments for room-scale VR. We evaluate our system via numerical simulations and real user studies.

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T9-like keyboards (i.e., 3 × 3 layouts) have been commonly used on small touchscreen devices to mitigate the problem of tapping tiny keys with imprecise finger touch (e.g., T9 is the default keyboard on Samsung Gear 2). In this paper, we proposed a computational approach to design optimal T9like layouts by considering three key factors: clarity, speed, and learnability. In particular, we devised a clarity metric to model the word collisions (i.e., words with identical tapping sequences), used the Fitts-Digraph model to predict speed, and introduced a Qwerty-bounded constraint to ensure high learnability. Founded upon rigorous mathematical optimization, our investigation led to Optimal-T9, an optimized T9like layout which outperformed the original T9 and other T9like layouts. A user study showed that its average input speed was 17% faster than T9 and 26% faster than a T9-like layout from literature. Optimal-T9 also drastically reduced the error rate by 72% over a regular Qwerty keyboard. Subjective ratings were in favor of Optimal-T9: it had the lowest physical, mental demands, and the best perceived-performance among all the tested keyboards. Overall, our investigation has led to a more efficient, and more accurate T9-like layout than the original T9. Such a layout would immediately benefit both T9-like keyboard users and small touchscreen device users.

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