REVEL is an augmented reality (AR) tactile technology that allows for change to the tactile feeling of real objects by augmenting them with virtual tactile textures using a device worn by the user. Unlike previous attempts to enhance AR environments with haptics, we neither physically actuate objects or use any force- or tactile-feedback devices, nor require users to wear tactile gloves or other apparatus on their hands. Instead, we employ the principle ofreverse electrovibrationwhere we inject a weak electrical signal anywhere on the user body creating an oscillating electrical field around the user's fingers. When sliding his or her fingers on a surface of the object, the user perceives highly distinctive tactile textures augmenting the physical object. By tracking the objects and location of the touch, we associate dynamic tactile sensations to the interaction context. REVEL is built upon our previous work on designing electrovibration-based tactile feedback for touch surfaces [Bau, et al. 2010]. In this paper we expand tactile interfaces based on electrovibration beyond touch surfaces and bring them into the real world. We demonstrate a broad range of application scenarios where our technology can be used to enhance AR interaction with dynamic and unobtrusive tactile feedback.

Gesture-based interfaces provide expert users with an efficient form of interaction but they require a learning effort for novice users. To address this problem, some on-line guiding techniques display all available gestures in response to partial input. However, partial input recognition algorithms are scale dependent while most gesture recognizers support scale independence (i.e., the same shape at different scales actually invokes the same command). We propose an algorithm for estimating the scale of any partial input in the context of a gesture recognition system and illustrate how it can be used to improve users' experience with gesture-based systems.

In this paper we present g-stalt, a gestural interface for interacting with video.g-stalt is built upon the g-speak spatial operating environment (SOE) from Oblong Industries.The version of g-stalt presented here is realized as a three-dimensional graphical space filled with over 60 cartoons.These cartoons can be viewed and rearranged along with their metadata using a specialized gesture set.gstalt is designed to be chirocentric, spatiotemporal, and telekinetic.

We present a new technology for enhancing touch interfaces with tactile feedback. The proposed technology is based on the electrovibration principle, does not use any moving parts and provides a wide range of tactile feedback sensations to fingers moving across a touch surface. When combined with an interactive display and touch input, it enables the design of a wide variety of interfaces that allow the user to feel virtual elements through touch. We present the principles of operation and an implementation of the technology. We also report the results of three controlled psychophysical experiments and a subjective user evaluation that describe and characterize users' perception of this technology. We conclude with an exploration of the design space of tactile touch screens using two comparable setups, one based on electrovibration and another on mechanical vibrotactile actuation.

Focus+context interaction techniques based on the metaphor of lenses are used to navigate and interact with objects in large information spaces. They provide in-place magnification of a region of the display without requiring users to zoom into the representation and consequently lose context. In order to avoid occlusion of its immediate surroundings, the magnified region is often integrated in the context using smooth transitions based on spatial distortion. Such lenses have been developed for various types of representations using techniques often tightly coupled with the underlying graphics framework. We describe a representation-independent solution that can be implemented with minimal effort in different graphics frameworks, ranging from 3D graphics to rich multiscale 2D graphics combining text, bitmaps, and vector graphics. Our solution is not limited to spatial distortion and provides a unified model that makes it possible to define new focus+context interaction techniques based on lenses whose transition is defined by a combination of dynamic displacement and compositing functions. We present the results of a series of user evaluations that show that one such new lens, the speed-coupled blending lens, significantly outperforms all others.

We describe OctoPocus, an example of a dynamic guide that combines on-screen feedforward and feedback to help users learn, execute and remember gesture sets. OctoPocus can be applied to a wide range of single-stroke gestures and recognition algorithms and helps users progress smoothly from novice to expert performance. We provide an analysis of the design space and describe the results of two experi-ments that show that OctoPocus is significantly faster and improves learning of arbitrary gestures, compared to con-ventional Help menus. It can also be adapted to a mark-based gesture set, significantly improving input time compared to a two-level, four-item Hierarchical Marking menu.