The IEEE VR Steering Committee congratulates and offers gratitude to the enormous efforts of the IEEE VR Conference Organizing Committees—with special recognition for the multiple years of hard work of the General Chairs, Carolina Cruz-Neira, Greg Welch, and Xubo Yang. To realize the conference requires a sizeable, motivated team of volunteers to work with the IEEE conference management team. Maintaining the conference’s status as the premier international virtual reality conference is a testament to the commitment of all the organizers and participants that make up the IEEE Virtual Reality community.

The IEEE VR Steering Committee congratulates and offers gratitude to the enormous efforts of the IEEE VR Conference Organizing Committees — with special recognition for the multiple years of hard work of the General Chairs, Xubo Yang, Kun Zhou, Tobias Langlotz, and Stephan Lukosch. To realize the conference requires a sizeable, motivated team of volunteers to work with the IEEE conference management team. Maintaining the conference's status as the premier international virtual reality conference is a testament to the commitment of all the organizers and participants that make up the IEEE Virtual Reality community.

International audience

It is our great pleasure to welcome you to Greenville, South Carolina, for the IEEE Conference on Virtual Reality (IEEE VR) 2016. This is the 18th year of the premiere conference in virtual reality and 3D interaction in the world, and we are proud to host it here in South Carolina. In recent years, the conference has travelled to Singapore, Orange County, USA, Orlando, USA, Minneapolis, USA, and Arles, France. During these years the conference has grown in many respects, yet the basic format of mostly a single-track technical session has changed little. This year's conference, however, will feature some notable departures from previous years while still keeping with our cherished traditions of the IEEE VR conference.

In mixed reality, real objects can be used to interact with virtual objects. However, unlike in the real world, real objects do not encounter any opposite reaction force when pushing against virtual objects. The lack of reaction force during manipulation prevents users from perceiving the mass of virtual objects. Although this could be addressed by equipping real objects with force-feedback devices, such a solution remains complex and impractical. In this work, we present a technique to produce an illusion of mass without any active force-feedback mechanism. This is achieved by simulating the effects of this reaction force in a purely visual way. A first study demonstrates that our technique indeed allows users to differentiate light virtual objects from heavy virtual objects. In addition, it shows that the illusion is immediately effective, with no prior training. In a second study, we measure the lowest mass difference (JND) that can be perceived with this technique. The effectiveness and ease of implementation of our solution provides an opportunity to enhance mixed reality interaction at no additional cost.

In this special issue of IEEE Transactions on Visualization and Computer Graphics (TVCG), we are pleased to present the long papers from the IEEE Virtual Reality Conference 2014 (IEEE VR 2014), held March 29–April 2, 2014 in Minneapolis, Minnesota, USA.

Presents the table of contents of the proceedings of the 2013 IEEE Virtual Reality Conference as published in this issue of the IEEE Transactions on Visualization and Computer Graphics .

The apers in this special issue were presented at the 2013 IEEE Virtual Reality Conference held March 16-20, 2013, in Orlando, Florida.

The articles in this special issue contain the full paper proceedings of the IEEE Virtual Reality Conference 2012 (IEEE VR 2012), held March 4-8, 2012 in Orange County, California.

In the present paper, we describe a virtual reality application developed for the study of unilateral spatial neglect, a post-stroke neurological disorder that results in failure to respond to stimuli presented contralaterally to the damaged hemisphere. Recently, it has been proposed that patients with unilateral spatial neglect experience sensorimotor decorrelation in the affected space. Consequently, it is possible that since the sensorimotor experience in the affected space is perturbed, patients avoid this space, which results in neglect behavior. Here, we evaluate this hypothesis using a virtual reality application built on the base of the Stringed Haptic Workbench, a large-scale visuo-haptic system. The results provide support for the hypothesis and demonstrate that the proposed application is suitable for the envisioned goal.

This paper describes a generalization of the god-object method for haptic interaction between rigid bodies. Our approach separates the computation of the motion of the six degree-of-freedom god-object from the computation of the force applied to the user. The motion of the god-object is computed using continuous collision detection and constraint-based quasi-statics, which enables high-quality haptic interaction between contacting rigid bodies. The force applied to the user is computed using a novel constraint-based quasi-static approach, which allows us to suppress force artifacts typically found in previous methods. The constraint-based force applied to the user, which handles any number of simultaneous contact points, is computed within a few microseconds, while the update of the configuration of the rigid god-object is performed within a few milliseconds for rigid bodies containing up to tens of thousands of triangles. Our approach has been successfully tested on complex benchmarks. Our results show that the separation into asynchronous processes allows us to satisfy the different update rates required by the haptic and visual displays. Force shading and textures can be added and enlarge the range of haptic perception of a virtual environment. This paper is an extension of [1].

This paper describes a generalization of the god-object method for haptic interaction between rigid bodies. Our approach separates the computation of the motion of the six degree-of-freedom god-object from the computation of the force applied to the user. The motion of the god-object is computed using continuous collision detection and constraint-based quasi-statics, which enables high-quality haptic interaction between contacting rigid bodies. The force applied to the user is computed using a novel constraint-based quasi-static approach, which allows us to suppress force artifacts typically found in previous methods. Our approach has been implemented on a 3.2 GHz Xeon bi-processor and has been successfully tested on complex benchmarks. Our results show that the separation into asynchronous processes allows us to satisfy the different update rates required by the haptic and the visual displays. The constraint-based force applied to the user, which handles any number of simultaneous contact points, is typically computed within a few microseconds, while the update of the configuration of the rigid god-object is performed within a few milliseconds for rigid bodies containing up to tens of thousands of triangles.

This paper proposes a new approach for adding haptic feedback on a workbench. The integration of a stringed haptic device is discussed.

Abstract The workbench is an interesting semi‐immersive configuration for interactive tasks. However, haptic feedback, i.e.force and tactile feedback, is one important cue which is missing. To the authors' knowledge, the sole proposedsolution consists in installing an arm force feedback device on one‐screen workbenches. This solution, however,has several drawbacks. The arm can perturb the stereoscopic display, cross virtual objects or hide parts of thevisualization space. Furthermore, the interaction space is limited by the size of the arm, which may also damagethe screen or perturb the electromagnetic tracking system. Some of these difficulties may even be worth with a two‐screenworkbench. This paper discusses an alternative solution, which consists in integrating a stringed hapticdevice on a workbench. This approach is less invasive, more flexible and well‐suited to a two‐screen workbench.

Application control in virtual environments (VE) is still an open field of research. The Command and Control Cube (C/sup 3/) developed by Grosjean et al. (2001) is a quick access menu for the VE configuration called workbench (a large screen displaying stereoscopic images). The C/sup 3/ presents two modes, one with the graphical display of the cubic structure associated to the C/sup 3/ and a blind mode for expert users, with no feedback. We conduct formal tests of the C/sup 3/ under four different conditions: the visual mode with the graphical display, the blind mode with no feedback and two additional conditions enhancing the expert blind mode: a tactile mode with the tactile feedback, of a Cyberglove/spl trade/ and a sound mode with a standard audio device. Results show that the addition of sound and tactile feedback is more disturbing to the users than the blind mode. The visual mode performs the best although the blind mode achieves some promising results.

Most of well-known approaches for rigid body simulations are formulated in the contact-space. Due to Gauss' principle of least constraints, the frictionless dynamics problems are formulated in a motion-space. While the two formulations are mathematically equivalent, they are not computationally equivalent. The motion-space formulation is better conditioned, always sparse, needs less memory, and avoids some unnecessary computations. A preliminary experimental comparison suggests that an algorithm operating in the motion-space takes advantage of sparsity to perform increasingly better than a contact-space algorithm as the average number of contact points per object increases.

A few years ago, Vanecek (1994) suggested to apply a variant of back-face culling to speed-up collision detection between polyhedral objects. However, Vanecek's method is linear in the number of faces in the object, which is unpractical for large models. This paper suggests to add some geometrical information to hierarchies of bounding volumes, typically used in collision detection, and perform conservative back-face culling at the bounding-volume level in constant time. The method described in this paper can be applied to complement any kind of bounding-volumes hierarchy and allows a trade-off between memory and speed. Preliminary experimental results suggest that the method allows a significant speed-up, especially in close proximity situations.

This paper introduces a fast continuous collision detection technique for polyhedral rigid bodies. As opposed to most collision detection techniques, the computation of the first contact time between two objects is inherently part of the algorithm. The method can thus robustly prevent objects interpenetrations or collisions misses, even when objects are thin or have large velocities. The method is valid for general objects (polygon soups), handles multiple moving objects and acyclic articulated bodies, and is efficient in low and high coherency situations. Moreover, the method can be used to speed up existent continuous collision detection methods for parametric or implicit rigid surfaces. The collision detection algorithms have been successfully coupled to a real-time dynamics simulator. Various experiments are conducted that show the method's ability to produce high-quality interaction (precise objects positioning for example) between models up to tens of thousands of triangles, which couldn't have been performed with previous continuous methods. Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Animation - Virtual Reality

Describes a psychophysical experiment designed to study the phenomenon of illusion which occurs with pseudo-haptic feedback, and to identify the moment when this illusion occurs: the "boundary of illusion". The subjects were given the task of deciding which of two virtual springs is the stiffer, these springs being simulated with a PHANToM/sup TM/ force feedback device and displayed on a monoscopic computer screen. The first spring had a realistic behavior, since its visual and haptic displacements were identical. The second spring-the pseudo-haptic one-was stiffer on a haptic basis, but sometimes less stiff on a visual basis. The data collected allowed us to calculate the visual point of subjective equality (PSE) between the two springs, which represents the boundary of the sensory illusion. On average, a high value of PSE turned out to be -24%. This value increased monotonically when the haptic difference between the springs increased. This implies that more visual deformation is necessary to compensate for large haptic differences and qualifies the notion of visual dominance. However, this boundary varies greatly depending on the subjects and their sensory integration strategy. The subjects were sensitive to this illusion to varying degrees. They were divided into different populations-from those who were "haptically oriented" to those who were "visually oriented".

This paper describes a new collision detection algorithm designed for interactive manipulation in virtual environments. Making some assumptions on object motion, the collision time between two objects can be computed by solving a polynomial equation whose degree is equal to or smaller than three.

This paper proposes a new interaction technique for positioning or moving 3D points, which is a basic task in geometric modeling and several other applications. These systems usually make use of a 2D interface with a 2D cursor. However positioning 3D points with a 2D cursor is often done by using several windows, each window displaying a different orthographic projection of the 3D space. This paper introduces the Metric Cursor, a multi-purpose 3D cursor which moves freely in the 3D space, requires only one window and provides the user with different helpful functionalities such as grids and some measurement capabilities.

This paper considers whether a passive isometric input device, such as a Spaceball/sup TM/, used together with visual feedback, could provide the operator with a pseudo-haptic feedback. For this aim, two psychophysical experiments have been conducted. The first experiment consisted of a compliance discrimination, between two virtual springs hand-operated by means of the Spaceball/sup TM/. In this experiment, the stiffness (or compliance) JND turned out to be 6%. The second experiment assessed stiffness discrimination between a virtual spring and the equivalent spring in reality. In this case, the stiffness (or compliance) JND was found to be 13.4%. These results are consistent with previous outcomes on manual discrimination of compliance. Consequently, this consistency reveals that the passive apparatus that was used can, to some extent, simulate haptic information. In addition, a final test indicated that the proprioceptive sense of the subjects was blurred by visual feedback. This gave them the illusion of using a nonisometric device.

Compared to most other virtual environments, the Responsive Workbench/sup TM/ offers a much better integration of the virtual and the real worlds. The Responsive Workbench/sup TM/ is a projection-based virtual environment with one horizontal table-sized projection plane. However interacting with these mixed 3D worlds remains a research challenge. This paper introduces a prop-like device, the virtual palette and describes the virtual remote control panel (VRCP), a two-handed interaction technique, based on the Virtual Palette, for controlling applications.

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Abstract We are interested in modelling the suface of very irregular objects known through a few planar polygonal cross‐sections. This problem is considered difficult when severe topology and morphology variations appear between neighbouring cross‐sections (multi‐branching, holes, disconnected areas). Only few methods deal with this problem in a systematic way. The paper describes an original method allowing to build, in a fully automatic and systematic way, an external surface with a valid topology in any case. It moreover allows to adjust details of the reconstructed surface in view of the morphologies and topologies of the various initial cross‐sectional contours. At first, a global correspondence is operated between each couple of adjacent cross‐sections by extracting polygonal areas of difference. Next steps are based on the computation in each area of difference of the bisector network, a well‐defined simplified generalised Voronoi diagram. This structure is used both for connecting initial contour points and for interpolating new intermediate portions of contours. It depends on the complexity of initial 2D shapes. Interpolation stage is then recursively operated until a satisfactory surface has been obtained or until a maximum number of new intermediate cross‐sectional contours have been built. The valid final suface is directly obtained by concatenating all the tiling areas of difference without need of any post processing step. The processing of several real data related to geological bodies or human organs has proved that the described method allows detailed modelling of irregular objects with very performing CPU times. The reconstruction appears insensitive to severe variations of the object shape, including apparitions of holes or disconnections.

Current research efforts focus on providing interactive techniques that make 3D concepts easy to use and accessible to large numbers of people. In this paper, a new interactive technique for animating deformable objects is presented. The technique allows easy specification and control of a class of deformations that cannot be produced by existing techniques without considerable human intervention.The methodology proposed relies on the Free-Form Deformation (FFD) technique. It makes use of a deformation tool that is animated like any other object.This approach provides a representation of the deformations independent of the surface geometry, and can be easily integrated into traditional hierarchical animation systems.

Current research efforts focus on providing more efficient and effective design methods for 3D modeling systems. In this paper a new deformation technique is presented. Among other things, arbitrarily shaped bumps can be designed and surfaces can be bent along arbitrarily shaped curves.The purpose of this research is to define a highly interactive and intuitive modeling technique for designers and stylists. A natural way of thinking is to mimic traditional trades, such as sculpturing and moulding.Furthermore, with this deformation technique, the modeling tool paradigm is introduced. The object is deformed with a user-defined deformation tool.This method is an extension of the Free-Form Deformation (FFD) technique proposed by Sederberg and Parry [17].

This paper describes an improvement of the ray-tracing algorithm. The new method takes advantage of a data structure which allows us to consider only the closest objects to the path of the ray. This technique can be applied to primary and secondary rays. Using this method, the run-time depends more on the complexity of the generated picture than on the complexity of the scene.

Abstract This paper presents an algorithm for random fields generation. The main idea of the paper is an improvement of the recursive technique presented by A. Fournier, D. Fussel and L. Carpenter in [4]. In order to ensure the continuity constraints on the boundaries of the cells generated at different stages of the algorithm, we show that it is possible to store the boundary values using a dynamic data structure. Random fields have been successfully used to model height fields or to display synthetic textures. In the second part of this paper we investigate the perspective mapping and clipping stages of random fields generation and display. At the end of the paper, some synthetic skies displayed using this technique are presented.