This paper presents a new reflectance model for rendering computer synthesized images. The model accounts for the relative brightness of different materials and light sources in the same scene. It describes the directional distribution of the reflected light and a color shift that occurs as the reflectance changes with incidence angle. The paper presents a method for obtaining the spectral energy distribution of the light reflected from an object made of a specific real material and discusses a procedure for accurately reproducing the color associated with the spectral energy distribution. The model is applied to the simulation of a metal and a plastic.

A reflectance model for computer graphics

The merger of game-based approaches and Virtual Reality (VR) environments that can enhance learning and training methodologies have a very promising future, reinforced by the widespread market-availability of affordable software and hardware tools for VR-environments. Rather than passive observers, users engage in those learning environments as active participants, permitting the development of exploration-based learning paradigms. There are separate reviews of VR technologies and serious games for educational and training purposes with a focus on only one knowledge area. However, this review covers 135 proposals for serious games in immersive VR-environments that are combinations of both VR and serious games and that offer end-user validation. First, an analysis of the forum, nationality, and date of publication of the articles is conducted. Then, the application domains, the target audience, the design of the game and its technological implementation, the performance evaluation procedure, and the results are analyzed. The aim here is to identify the factual standards of the proposed solutions and the differences between training and learning applications. Finally, the study lays the basis for future research lines that will develop serious games in immersive VR-environments, providing recommendations for the improvement of these tools and their successful application for the enhancement of both learning and training tasks.

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A review of immersive virtual reality serious games to enhance learning and training

Thanks to the increasing availability of consumer head-mounted displays, educational applications of immersive VR could now reach to the general public, especially if they include gaming elements (immersive serious games). Safety education of citizens could be a particularly promising domain for immersive serious games, because people tend not to pay attention to and benefit from current safety materials. In this paper, we propose an HMD-based immersive game for educating passengers about aviation safety that allows players to experience a serious aircraft emergency with the goal of surviving it. We compare the proposed approach to a traditional aviation safety education method (the safety card) used by airlines. Unlike most studies of VR for safety knowledge acquisition, we do not focus only on assessing learning immediately after the experience but we extend our attention to knowledge retention over a longer time span. This is a fundamental requirement, because people need to retain safety procedures in order to apply them when faced with danger. A knowledge test administered before, immediately after and one week after the experimental condition showed that the immersive serious game was superior to the safety card. Moreover, subjective as well as physiological measurements employed in the study showed that the immersive serious game was more engaging and fear-arousing than the safety card, a factor that can contribute to explain the obtained superior retention, as we discuss in the paper.

Assessing Knowledge Retention of an Immersive Serious Game vs. a Traditional Education Method in Aviation Safety

The purpose of this research was to amend the Vividness of Movement Imagery Questionnaire (VMIQ; Isaac, Marks, & Russell, 1986) in line with contemporary imagery modality and perspective conceptualizations, and to test the validity of the amended questionnaire (i.e., the VMIQ-2). Study 1 had 351 athletes complete the 3-factor (internal visual imagery, external visual imagery, and kinesthetic imagery) 24-item VMIQ-2. Following single-factor confirmatory factor analyses and item deletion, a 12-item version was subject to correlated traits / correlated uniqueness (CTCU) analysis. An acceptable fit was revealed. Study 2 used a different sample of 355 athletes. The CTCU analysis confirmed the factorial validity of the 12-item VMIQ-2. In Study 3, the concurrent and construct validity of the VMIQ-2 was supported. Taken together, the results of the 3 studies provide preliminary support for the revised VMIQ-2 as a psychometrically valid questionnaire.

Movement Imagery Ability: Developmentand Assessment of a Revised Versionof the Vividness of Movement ImageryQuestionnaire

The aim of this article is to analyze and review the scientific literature relating to the application of Augmented Reality (AR) technology in industry. AR technology is becoming increasingly diffu...

Augmented reality technology in the manufacturing industry: A review of the last decade

Background
The development of modern surgical simulators is highly challenging as they must support complex simulation environments. The demand for higher realism in such simulators has driven researchers to adopt physics-based models which are computationally very demanding. This poses a major problem since real time interactions must permit graphical updates of 30 Hz and a much higher rate of 1 kHz for force feedback (haptics). Recently several physics engines have been developed which offer multi-physics simulation capabilities including rigid and deformable bodies, cloth and fluids. While such physics engines provide unique opportunities for the development of surgical simulators, their higher latencies, compared to what is necessary for real time graphics and haptics, offer significant barriers to their use in interactive simulation environments.

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Using the PhysX engine for physics‐based virtual surgery with force feedback

We present an assessment of asymmetric interactions in Collaborative Virtual Environments (CVEs). In our asymmetric setup, two co-located users interact with virtual 3D objects, one in immersive Virtual Reality (VR) and the other in mobile Augmented Reality (AR). We conducted a study with 36 participants to evaluate performance and collaboration aspects of pair work, and compare it with two symmetric scenarios, either with both users in immersive VR or mobile AR. To perform this experiment, we adopt a collaborative AR manipulation technique from literature and develop and evaluate a VR manipulation technique of our own. Our results indicate that pairs in asymmetric VR-AR achieved significantly better performance than the AR symmetric condition, and similar performance to VR symmetric. Regardless of the condition, pairs had similar work participation indicating a high cooperation level even when there is a visualization and interaction asymmetry between the participants.

Characterizing Asymmetric Collaborative Interactions in Virtual and Augmented Realities

https://www.inf.ufrgs.br/~amaciel/publications/docs/is4tm2003.pdf

Deformable tissue parameterized by properties of real biological tissue

Due to the perceptual characteristics of the head, vibrotactile Head-mounted Displays are built with low actuator density. Therefore, vibrotactile guidance is mostly assessed by pointing towards objects in the azimuthal plane. When it comes to multisensory interaction in 3D environments, it is also important to convey information about objects in the elevation plane. In this paper, we design and assess a haptic guidance technique for 3D environments. First, we explore the modulation of vibration frequency to indicate the position of objects in the elevation plane. Then, we assessed a vibrotactile HMD made to render the position of objects in a 3D space around the subject by varying both stimulus loci and vibration frequency. Results have shown that frequencies modulated with a quadratic growth function allowed a more accurate, precise, and faster target localization in an active head pointing task. The technique presented high usability and a strong learning effect for a haptic search across different scenarios in an immersive VR setup.

Designing a Vibrotactile Head-Mounted Display for Spatial Awareness in 3D Spaces

Tangible objects are used in virtual reality (VR) and augmented reality (AR) to enhance haptic information on the general shape of virtual objects. However, they are often passive or unable to simulate rich varying mechanical properties. This article studies the effect of combining simple passive tangible objects and wearable haptics for improving the display of varying stiffness, friction, and shape sensations in these environments. By providing timely cutaneous stimuli through a wearable finger device, we can make an object feel softer or more slippery than it really is, and we can also create the illusion of encountering virtual bumps and holes. We evaluate the proposed approach carrying out three experiments with human subjects. Results confirm that we can increase the compliance of a tangible object by varying the pressure applied through a wearable device. We are also able to simulate the presence of bumps and holes by providing timely pressure and skin stretch sensations. Altering the friction of a tangible surface showed recognition rates above the chance level, albeit lower than those registered in the other experiments. Finally, we show the potential of our techniques in an immersive medical palpation use case in VR. These results pave the way for novel and promising haptic interactions in VR, better exploiting the multiple ways of providing simple, unobtrusive, and inexpensive haptic displays.

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Anderson Maciel

Papers

Using the PhysX engine for physics‐based virtual surgery with force feedback

Characterizing Asymmetric Collaborative Interactions in Virtual and Augmented Realities

Deformable tissue parameterized by properties of real biological tissue

Designing a Vibrotactile Head-Mounted Display for Spatial Awareness in 3D Spaces

Altering the Stiffness, Friction, and Shape Perception of Tangible Objects in Virtual Reality Using Wearable Haptics