Hrvoje Benko

MirageTable: freehand interaction on a projected augmented reality tabletop

Instrumented with a single depth camera, a stereoscopic projector, and a curved screen, MirageTable is an interactive system designed to merge real and virtual worlds into a single spatially registered experience on top of a table. Our depth camera tracks the users eyes and performs a real-time capture of both the shape and the appearance of any object placed in front of the camera (including users body and hands). This real-time capture enables perspective stereoscopic 3D visualizations to a single user that account for deformations caused by physical objects on the table. In addition, the user can interact with virtual objects through physically-realistic freehand actions without any gloves, trackers, or instruments. We illustrate these unique capabilities through three application examples: virtual 3D model creation, interactive gaming with real and virtual objects, and a 3D teleconferencing experience that not only presents a 3D view of a remote person, but also a seamless 3D shared task space. We also evaluated the users perception of projected 3D objects in our system, which confirmed that the users can correctly perceive such objects even when they are projected over different background colors and geometries (e.g., gaps, drops).

Mutual disambiguation of 3D multimodal interaction in augmented and virtual reality

We describe an approach to 3D multimodal interaction in immersive augmented and virtual reality environments that accounts for the uncertain nature of the information sources. The resulting multimodal system fuses symbolic and statistical information from a set of 3D gesture, spoken language, and referential agents. The referential agents employ visible or invisible volumes that can be attached to 3D trackers in the environment, and which use a time-stamped history of the objects that intersect them to derive statistics for ranking potential referents. We discuss the means by which the system supports mutual disambiguation of these modalities and information sources, and show through a user study how mutual disambiguation accounts for over 45% of the successful 3D multimodal interpretations. An accompanying video demonstrates the system in action.

Sphere: multi-touch interactions on a spherical display

Sphere is a multi-user, multi-touch-sensitive spherical display in which an infrared camera used for touch sensing shares the same optical path with the projector used for the display. This novel configuration permits: (1) the enclosure of both the projection and the sensing mechanism in the base of the device, and (2) easy 360-degree access for multiple users, with a high degree of interactivity without shadowing or occlusion. In addition to the hardware and software solution, we present a set of multi-touch interaction techniques and interface concepts that facilitate collaborative interactions around Sphere. We designed four spherical application concepts and report on several important observations of collaborative activity from our initial Sphere installation in three high-traffic locations.

RoomAlive: magical experiences enabled by scalable, adaptive projector-camera units

RoomAlive is a proof-of-concept prototype that transforms any room into an immersive, augmented entertainment experience. Our system enables new interactive projection mapping experiences that dynamically adapts content to any room. Users can touch, shoot, stomp, dodge and steer projected content that seamlessly co-exists with their existing physical environment. The basic building blocks of RoomAlive are projector-depth camera units, which can be combined through a scalable, distributed framework. The projector-depth camera units are individually auto-calibrating, self-localizing, and create a unified model of the room with no user intervention. We investigate the design space of gaming experiences that are possible with RoomAlive and explore methods for dynamically mapping content based on room layout and user position. Finally we showcase four experience prototypes that demonstrate the novel interactive experiences that are possible with RoomAlive and discuss the design challenges of adapting any game to any room.

Grips and gestures on a multi-touch pen

This paper explores the interaction possibilities enabled when the barrel of a digital pen is augmented with a multi-touch sensor. We present a novel multi-touch pen (MTPen) prototype and discuss its alternate uses beyond those of a standard stylus, such as allowing new touch gestures to be performed using the index finger or thumb and detecting how users grip the device as a mechanism for mode switching. We also discuss the hardware and software implementation challenges in realizing our prototype, and showcase how one can combine different grips (tripod, relaxed tripod, sketch, wrap) and gestures (swipe and double tap) to enable new interaction techniques with the MTPen in a prototype drawing application. One specific aim is the elimination of some of the comfort problems associated with existing auxiliary controls on digital pens. Mechanical controls such as barrel buttons and barrel scroll wheels work best in only a few specific hand grips and pen rotations. Comparatively, our gestures can be successfully and comfortably performed regardless of the rotation of the pen or how the user grips it, offering greater flexibility in use. We describe a formal evaluation comparing MTPen gestures against the use of a barrel button for mode switching. This study shows that both swipe and double tap gestures are comparable in performance to commonly employed barrel buttons without its disadvantages.

ShadowGuides: visualizations for in-situ learning of multi-touch and whole-hand gestures

We present ShadowGuides, a system for in-situ learning of multi-touch and whole-hand gestures on interactive surfaces. ShadowGuides provides on-demand assistance to the user by combining visualizations of the users current hand posture as interpreted by the system (feedback) and available postures and completion paths necessary to finish the gesture (feedforward). Our experiment compared participants learning gestures with ShadowGuides to those learning with video-based instruction. We found that participants learning with ShadowGuides remembered more gestures and expressed significantly higher preference for the help system.

Collaborative mixed reality visualization of an archaeological excavation

We present VITA (visual interaction tool for archaeology), an experimental collaborative mixed reality system for offsite visualization of an archaeological dig. Our system allows multiple users to visualize the dig site in a mixed reality environment in which tracked, see-through, head-worn displays are combined with a multi-user, multi-touch, projected table surface, a large screen display, and tracked hand-held displays. We focus on augmenting existing archaeological analysis methods with new ways to organize, visualize, and combine the standard 2D information available from an excavation (drawings, pictures, and notes) with textured, laser range-scanned 3D models of objects and the site itself. Users can combine speech, touch, and 3D hand gestures to interact multimodally with the environment. Preliminary user tests were conducted with archaeology researchers and students, and their feedback is presented here.

LightGuide: projected visualizations for hand movement guidance

LightGuide is a system that explores a new approach to gesture guidance where we project guidance hints directly on a users body. These projected hints guide the user in completing the desired motion with their body part which is particularly useful for performing movements that require accuracy and proper technique, such as during exercise or physical therapy. Our proof-of-concept implementation consists of a single low-cost depth camera and projector and we present four novel interaction techniques that are focused on guiding a users hand in mid-air. Our visualizations are designed to incorporate both feedback and feedforward cues to help guide users through a range of movements. We quantify the performance of LightGuide in a user study comparing each of our on-body visualizations to hand animation videos on a computer display in both time and accuracy. Exceeding our expectations, participants performed movements with an average error of 21.6mm, nearly 85% more accurately than when guided by video.

Steerable augmented reality with the beamatron

Steerable displays use a motorized platform to orient a projector to display graphics at any point in the room. Often a camera is included to recognize markers and other objects, as well as user gestures in the display volume. Such systems can be used to superimpose graphics onto the real world, and so are useful in a number of augmented reality and ubiquitous computing scenarios. We contribute the Beamatron, which advances steerable displays by drawing on recent progress in depth camera-based interactions. The Beamatron consists of a computer-controlled pan and tilt platform on which is mounted a projector and Microsoft Kinect sensor. While much previous work with steerable displays deals primarily with projecting corrected graphics onto a discrete set of static planes, we describe computational techniques that enable reasoning in 3D using live depth data. We show two example applications that are enabled by the unique capabilities of the Beamatron: an augmented reality game in which a player can drive a virtual toy car around a room, and a ubiquitous computing demo that uses speech and gesture to move projected graphics throughout the room.

Haptic Retargeting: Dynamic Repurposing of Passive Haptics for Enhanced Virtual Reality Experiences

Manipulating a virtual object with appropriate passive haptic cues provides a satisfying sense of presence in virtual reality. However, scaling such experiences to support multiple virtual objects is a challenge as each one needs to be accompanied with a precisely-located haptic proxy object. We propose a solution that overcomes this limitation by hacking human perception. We have created a framework for repurposing passive haptics, called haptic retargeting, that leverages the dominance of vision when our senses conflict. With haptic retargeting, a single physical prop can provide passive haptics for multiple virtual objects. We introduce three approaches for dynamically aligning physical and virtual objects: world manipulation, body manipulation and a hybrid technique which combines both world and body manipulation. Our study results indicate that all our haptic retargeting techniques improve the sense of presence when compared to typical wand-based 3D control of virtual objects. Furthermore, our hybrid haptic retargeting achieved the highest satisfaction and presence scores while limiting the visible side-effects during interaction.