Fitts's law facilitates approximate comparisons of target acquisition performance across a variety of settings. Conceptually, also the index of difficulty of 3D object manipulation with six degrees of freedom can be computed, which allows the comparison of results from different studies. Prior experiments, however, often revealed much worse performance than one would reasonably expect on this basis. We argue that this discrepancy stems from confounding variables and show how Fitts's law and related research methods can be applied to isolate and identify relevant factors of motor performance in 3D manipulation tasks. The results of a formal user study ( n=21) demonstrate competitive performance in compliance with Fitts's model and provide empirical evidence that simultaneous 3D rotation and translation can be beneficial.

We present a novel collaborative virtual reality system that offers multiple immersive 3D views at large 3D scenes. The physical setup consists of two synchronized multi-user 3D displays: a tabletop and a large vertical projection screen. These displays afford different presentations of the shared 3D scene. The wall display lends itself to the egocentric exploration at 1:1 scale, while the tabletop affords an allocentric overview. Additionally, handheld 3D portals facilitate the personal exploration of the scene, the comparison of views, and the exchange with others. Our developments enable seamless 3D interaction across these independent 3D views. This requires the simultaneous representation of user input in the different viewing contexts. However, the resulting interactions cannot be executed independently. The application must coordinate the interactions and resolve potential ambiguities to provide plausible effects. We analyze and document the challenges of seamless 3D interaction across multiple independent viewing windows, propose a high-level software design to realize the necessary functionality, and apply the design to a set of interaction tools. Our setup was tested in a formal user study, which revealed general advantages of collaborative 3D data exploration with multiple views in terms of user preference, comfort, and task performance.

We present the collaborative Virtual Reality Neurorobotics Lab, which allows multiple collocated and remote users to experience, discuss and participate in neurorobotic experiments in immersive virtual reality. We describe the coupling of the Neurorobotics Platform of the Human Brain Project with our collaborative virtual reality and 3D telepresence infrastructure and highlight future opportunities arising from our work for research on direct human interaction with simulated robots and brains.

We present a comprehensive multitouch input mapping for 3D navigation of multiscale 3D models. In contrast to prior work, our technique offers explicit control over 3D rotation, 3D translation, and uniform scaling with manipulative gestures that do not require graphical widgets. Our proposed technique is consistent with the established RST mapping (rotation, scaling, translation) for 2D mul-titouch input and follows suggestions from prior work on multitouch 3D interaction. Our implementation includes a rendering technique that can reduce perceptual conflicts of 3D touch input on stereoscopic displays. We also report on two user studies that informed the suggested interaction design and confirmed its usability.

Many recent head-mounted display applications and games implement a range-restricted variant of teleportation for exploring virtual environments. This travel metaphor referred to as jumping only allows to teleport to locations in the currently visible part of the scene. In this paper, we present a formal description and classification scheme for teleportation techniques and its application to the classification of jumping. Furthermore, we present the results of a user study (N=24) that compared jumping to the more conventional steering with respect to spatial updating and simulator sickness. Our results show that despite significantly faster travel times during jumping, a majority of participants (75%) achieved similar spatial updating accuracies in both conditions (mean difference 0.02°, =5.05°. In addition, jumping induced significantly less simulator sickness, which altogether justifies it as an alternative to steering for the exploration of immersive virtual environments. However, application developers should be aware that spatial updating during jumping may be impaired for individuals.

Photoportals build on digital photography as a unifying metaphor for reference-based interaction in 3D virtual environments. Virtual photos and videos serve as threedimensional references to objects, places, moments in time and activities of users. Our Photoportals also provide access to intermediate or alternative versions of a scenario and allow the review of recorded task sequences that include life-size representations of the captured users. We propose to exploit such references to structure collaborative activities of collocated and remote users. Photoportals offer additional access points for multiple users and encourage mutual support through the preparation and provision of references for manipulation and navigation tasks. They support the pattern of territoriality with configurable space representations that can be used for private interaction, as well as be shared and exchanged with others.

Our vision is that regardless of future variations in the interior of airplane cabins, we can utilize ever-advancing state-of-the-art virtual and mixed reality technologies with the latest research in neuroscience and psychology to achieve high levels of comfort for passengers. Current surveys on passenger's experience during air travel reveal that they are least satisfied with the amount and effectiveness of their personal space, and their ability to work, sleep or rest. Moreover, considering current trends it is likely that the amount of available space is likely to decrease and therefore the passenger's physical comfort during a flight is likely to worsen significantly. Therefore, the main challenge is to enable the passengers to maintain a high level of comfort and satisfaction while being placed in a restricted physical space.

We present a novel immersive telepresence system that allows distributed groups of users to meet in a shared virtual 3D world. Our approach is based on two coupled projection-based multi-user setups, each providing multiple users with perspectively correct stereoscopic images. At each site the users and their local interaction space are continuously captured using a cluster of registered depth and color cameras. The captured 3D information is transferred to the respective other location, where the remote participants are virtually reconstructed. We explore the use of these virtual user representations in various interaction scenarios in which local and remote users are face-to-face, side-by-side or decoupled. Initial experiments with distributed user groups indicate the mutual understanding of pointing and tracing gestures independent of whether they were performed by local or remote participants. Our users were excited about the new possibilities of jointly exploring a virtual city, where they relied on a world-in-miniature metaphor for mutual awareness of their respective locations.

Stereoscopic multi-user systems provide multiple users with individual views of a virtual environment. We developed a new projection-based stereoscopic display for six users, which employs six customized DLP projectors for fast time-sequential image display in combination with polarization. Our intelligent high-speed shutter glasses can be programmed from the application to adapt to the situation. For instance, it does this by staying open if users do not look at the projection screen or switch to a VIP high brightness mode if less than six users use the system. Each user is tracked and can move freely in front of the display while perceiving perspectively correct views of the virtual environment. Navigating a group of six users through a virtual world leads to situations in which the group will not fit through spatial constrictions. Our augmented group navigation techniques ameliorate this situation by fading out obstacles or by slightly redirecting individual users along a collision-free path. While redirection goes mostly unnoticed, both techniques temporarily give up the notion of a consistent shared space. Our user study confirms that users generally prefer this trade-off over naïve approaches.

The Globefish is a novel desktop input device for three-dimensional object manipulation and viewpoint navigation. It consists of an elastically suspended 3D trackball, which provides a natural mapping for position-controlled 3D rotations. Rate-controlled 3D translations are performed by pushing the trackball into the appropriate direction. The device is manipulated by the fingertips allowing for precise interaction with virtual objects. The Globefish was designed for 3D graphics applications such as computer aided design (CAD), digital content creation (DCC) and 3D games.

This paper investigates the usability of tracked wands equipped with additional input sensors for system control tasks in 3D interaction scenarios. We integrated a thumb-operated circular touchpad into a hand-held wand and compared the performance of our input device to common ray-based interaction in a menu selection and parameter adjustment task. The results show that both interfaces can be highly efficient, but ray-based interaction is only competitive if large-sized graphical interface representations are provided. In contrast, touchpad input performs well independent of the size of the graphical elements due to proprioceptive and tactile feedback.