Analyzing place metaphors in 3D educational collaborative virtual environments

In the recent years, the usage of three dimensional (3D) collaborative virtual environments (CVEs) for educational purposes has increased. The metaphors behind the design of virtual places are quite diverse, from replication of real universities to art museums and scientific labs. This paper reports the results of a case study where the students of our university, as a part of their course assignment, analyzed place metaphors used in a range of 3D educational CVEs vs. the corresponding educational goals. The students suggested a design for a virtual campus representing the Norwegian University of Science and Technology (NTNU). The results of this study provide some suggestions concerning the characterization of different design features in educational CVEs and the suitability of such features for different educational goals. Also, a preliminary set of design guidelines for an ideal virtual campus representing a real university is presented. Finally, some challenges associated with using 3D CVEs in various educational situations are discussed.     

Height effects in real and virtual environments

The study compared human perceptions of height, danger, and anxiety, as well as skin conductance and heart rate responses and postural instability effects, in real and virtual height environments. The 24 participants (12 men, 12 women), whose average age was 23.6 years, performed "lean-over-the-railing" and standing tasks on real and comparable virtual balconies, using a surround-screen virtual reality (SSVR) system. The results indicate that the virtual display of elevation provided realistic perceptual experience and induced some physiological responses and postural instability effects comparable to those found in a real environment. It appears that a simulation of elevated work environment in a SSVR system, although with reduced visual fidelity, is a valid tool for safety research. Potential applications of this study include the design of virtual environments that will help in safe evaluation of human performance at elevation, identification of risk factors leading to fall incidents, and assessment of new fall prevention strategies.     

Locales: supporting large multiuser virtual environments

Creators of multiuser virtual environments naturally desire to make them large in spatial extent, large in numbers of objects, and large in numbers of users interacting with the environment. However, doing so creates several problems: efficiently managing the flow of large amounts of data between large numbers of users, representing precise position and velocity information about objects arrayed across a large volume of space, and allowing designers to create parts of a virtual environment separately and combine them together later. The concept of locales is based on the idea that even in a very large virtual world, most of what a single user can observe at a given moment is nevertheless local in nature. You would expect a large virtual world to be large primarily because, like a city, it combines a large number of relatively small, localized activities not because it contains very large individual activities. Locales divide a virtual world into chunks that can be processed separately. This division is purely an implementation issue-it is not apparent to the user. A user sees several locales at once-generally the locale containing the user's point of view and those neighboring it. The user does not see any seams between the locales nor any abrupt changes as the point of view moves from one locale to another, thereby changing the neighborhood set     

Predicting audio step feedback for real walking in virtual environments

When navigating in virtual environments by using real walking, the correct auditory step feedback is usually ignored, although this could give more information to the user about the ground he is walking on. One reason for this is time constraints that hinder a replay of a walking sound synchronous to the haptic step feedback when walking. In order to add a matching step feedback to virtual environments, this paper introduces a calibration‐free system, which can predict the occurrence time of a step‐down event based on an analysis of the user's gait. For detecting reliable characteristics of the gait, accelerometers and gyroscopes are used, which are mounted on the user's foot. Because the proposed system is capable of detecting the characteristic events in the foot's swing phase, it allows a prediction that gives enough time to replay sound synchronous to the haptic sensation of walking. In order to find the best prediction regarding prediction time and accuracy, data gathered in an experiment is analyzed regarding reliably occurring characteristics in the human gait. Based on this, a suitable prediction algorithm is proposed. Copyright © 2014 John Wiley & Sons, Ltd.     

Performance of a skilled motor task in virtual and real environments

Three experiments compared the performances of adult participants (three groups of 10) on a perceptuo-motor task in both real world (RW) and virtual environments (VEs). The task involved passing a hoop over a bent wire course, and three versions of the task were used: a 3-D wire course with no background, a flattened version of the 3-D course (2½-D course) with no background, and the 2½-D course with added background to provide spatial context. In all three experiments the participants had to prevent the hoop from touching the wire as they moved it. In the first experiment, the VE condition produced about 18 times more errors than the RW task. The VE 2½-D task was found to be as difficult as the 3-D, and the 2½-D with the added background produced more errors than the other two experiments. Taken together, the experiments demonstrate the difficulty of performing fine motor tasks in VEs, a phenomenon that has not been given due attention in many previous studies of motor control in VEs.     

Performance of a skilled motor task in virtual and real environments

Three experiments compared the performances of adult participants (three groups of 10) on a perceptuo-motor task in both real world (RW) and virtual environments (VEs). The task involved passing a hoop over a bent wire course, and three versions of the task were used: a 3-D wire course with no background, a flattened version of the 3-D course (2(1/2)-D course) with no background, and the 2(1/2)-D course with added background to provide spatial context. In all three experiments the participants had to prevent the hoop from touching the wire as they moved it. In the first experiment, the VE condition produced about 18 times more errors than the RW task. The VE 2(1/2)-D task was found to be as difficult as the 3-D, and the 2(1/2)-D with the added background produced more errors than the other two experiments. Taken together, the experiments demonstrate the difficulty of performing fine motor tasks in VEs, a phenomenon that has not been given due attention in many previous studies of motor control in VEs.     

VLOD: high-fidelity walkthrough of large virtual environments

We present visibility computation and data organization algorithms that enable high-fidelity walkthroughs of large 3D geometric data sets. A novel feature of our walkthrough system is that it performs work proportional only to the required detail in visible geometry at the rendering time. To accomplish this, we use a precomputation phase that efficiently generates per cell vLOD: the geometry visible from a view-region at the right level of detail. We encode changes between neighboring cells' vLODs, which are not required to be memory resident. At the rendering time, we incrementally construct the vLOD for the current view-cell and render it. We have a small CPU and memory requirement for rendering and are able to display models with tens of millions of polygons at interactive frame rates with less than one pixel screen-space deviation and accurate visibility.     

Camera space shadow maps for large virtual environments

This paper presents a new single-pass shadow mapping technique that achieves better quality than the approaches based on perspective warping, such as perspective, light-space, and trapezoidal shadow maps. The proposed technique is appropriate for real-time rendering of large virtual environments that include dynamic objects. By performing operations in camera space, this solution successfully handles the general and the dueling frustum cases and produces high-quality shadows even for extremely large scenes. This paper also presents a fast nonlinear projection technique for shadow map stretching that enables complete utilization of the shadow map by eliminating wastage. The application of stretching results in a significant reduction in unwanted perspective aliasing, commonly found in all shadow mapping techniques. Technique is compared with other shadow mapping techniques, and the benefits of the proposed method are presented. The proposed shadow mapping technique is simple and flexible enough to handle most of the special scenarios. An API for a generic shadow mapping solution is presented. This API simplifies the generation of fast and high-quality shadows.     

The CyCab: a car-like robot navigating autonomously and safely among pedestrians

The recent development of a new kind of public transportation system relies on a particular double-steering kinematic structure enhancing manoeuvrability in cluttered environments such as downtown areas. We call bi-steerable car a vehicle showing this kind of kinematics. Endowed with autonomy capacities, the bi-steerable car ought to combine suitably and safely a set of abilities: simultaneous localisation and environment modelling, motion planning and motion execution amidst moderately dynamic obstacles. In this paper we address the integration of these four essential autonomy abilities into a single application. Specifically, we aim at reactive execution of planned motion. We address the fusion of controls issued from the control law and the obstacle avoidance module using probabilistic techniques.     

Designing presence for real locomotion in immersive virtual environments: an affordance-based experiential approach

This paper describes a framework for designing systems for real locomotion in virtual environments (VEs) in order to achieve an intense sense of presence. The main outcome of the present research is a list of design features that the virtual reality technology should have in order to achieve such a goal. To identify these features, an approach based on the combination of two design strategies was followed. The first was based on the theory of affordances and was utilized to design a generic VE in which the affordances of the corresponding real environment could be evoked. The second was the experiential design applied to VEs and was utilized to create an experience of locomotion corresponding to that achievable in a real environment. These design strategies were chosen because of their potential to enhance the sense of presence. The proposed list of features can be utilized as an instrument that allows VE designers to evaluate the maturity of their systems and to pinpoint directions for future developments. A survey analysis was performed using the proposed framework, which involved three case studies to determine how many features of the proposed framework were present and their status. The result of such analysis represented a measure of the completeness of the systems design, of the affordances provided to the user, and a prediction of the sense of presence.     

Towards perceptual fidelity: Slant perception in real and interactive virtual environments

An innovative motoric measure of slant based on gait is proposed as the angle between the foot and the walking surface during walking. This work investigates whether the proposed action-based measure is affected by factors such as material and inclination of the walking surface. Experimental studies were conducted in a real environment set-up and in its virtual simulation counterpart evaluating behavioural fidelity and user performance in ecologically-valid simulations. In the real environment, the measure slightly overestimated the inclined path whereas in the virtual environment it slightly underestimated the inclined path. The results imply that the proposed slant measure is modulated by motoric caution. Since the “reality” of the synthetic environment was relatively high, performance results should have revealed the same degree of caution as in the real world, however, that was not the case. People become more cautious when the ground plane was steep, slippery, or virtual.     

Training in virtual environments: transfer to real world tasks and equivalence to real task training

Virtual environments (VEs) are extensively used in training but there have been few rigorous scientific investigations of whether and how skills learned in a VE are transferred to the real world. This research aimed to measure and evaluate what is transferring from training a simple sensorimotor task in a VE to real world performance. In experiment 1, real world performances after virtual training, real training and no training were compared. Virtual and real training resulted in equivalent levels of post-training performance, both of which significantly exceeded task performance without training. Experiments 2 and 3 investigated whether virtual and real trained real world performances differed in their susceptibility to cognitive and motor interfering tasks (experiment 2) and in terms of spare attentional capacity to respond to stimuli and instructions which were not directly related to the task (experiment 3). The only significant difference found was that real task performance after training in a VE was less affected by concurrently performed interference tasks than was real task performance after training on the real task. This finding is discussed in terms of the cognitive load characteristics of virtual training. Virtual training therefore resulted in equivalent or even better real world performance than real training in this simple sensorimotor task, but this finding may not apply to other training tasks. Future research should be directed towards establishing a comprehensive knowledge of what is being transferred to real world performance in other tasks currently being trained in VEs and investigating the equivalence of virtual and real trained performances in these situations.     

Training in virtual environments: transfer to real world tasks and equivalence to real task training

Virtual environments (VEs) are extensively used in training but there have been few rigorous scientific investigations of whether and how skills learned in a VE are transferred to the real world. This research aimed to measure and evaluate what is transferring from training a simple sensorimotor task in a VE to real world performance. In experiment 1, real world performances after virtual training, real training and no training were compared. Virtual and real training resulted in equivalent levels of post-training performance, both of which significantly exceeded task performance without training. Experiments 2 and 3 investigated whether virtual and real trained real world performances differed in their susceptibility to cognitive and motor interfering tasks (experiment 2) and in terms of spare attentional capacity to respond to stimuli and instructions which were not directly related to the task (experiment 3). The only significant difference found was that real task performance after training in a VE was less affected by concurrently performed interference tasks than was real task performance after training on the real task. This finding is discussed in terms of the cognitive load characteristics of virtual training. Virtual training therefore resulted in equivalent or even better real world performance than real training in this simple sensorimotor task, but this finding may not apply to other training tasks. Future research should be directed towards establishing a comprehensive knowledge of what is being transferred to real world performance in other tasks currently being trained in VEs and investigating the equivalence of virtual and real trained performances in these situations.     

Integration of virtual and real environments for engineering service-oriented manufacturing systems

Engineering frameworks are currently required to support the easy, low-cost, modular and integrated development of manufacturing systems addressing the emergent requirements of re-configurability, responsiveness and robustness. This paper discusses the integration of 2D/3D digital software tools with Petri net based service-oriented frameworks to allow the design, configuration, analysis, validation, simulation, monitoring and control of manufacturing systems in a virtual environment and its posterior smooth migration into the real ??physical?? environment. An experimental case study was implemented to validate the proposed concepts, using the Continuum platform to design, compose, analyze, validate and simulate the Petri nets based service-oriented manufacturing control system, and the Delmia Automation^TM software suite to support the rapid prototyping and the easy simulation of the designed control solution. The experimental results prove several aspects of the proposed approach, notably the smooth migration between the design and the operation phases, one of the main objectives of the work.     

Selection of key visual cues in real and virtual environments for assembly tasks

Previous research identified that learning assembly tasks in Virtual Environments (VEs) is more difficult than in Real Environments (REs). This work's objective is to identify the key visual areas for both environments when performing an assembly task for ten consecutive cycles, when following visual instructions and when having visual distractors. Using an eye-tracker, we identified the key visual areas required for an assembly task in both environments. Results indicate that practice allowed participants to reduce their assembly time in both environments. They also indicate that two areas, Assembly Area and Blocks, concentrated a higher proportion of eye-fixations; 59.98% for REs and 81.48% for VEs, with a statistically significant observation difference between environments (t-test value = −14.23, with p-value <0.00001 and Cohen's d = 6.36). We conclude that participants considered the same key visual areas for both environments and that VE interaction has a significant role in observation behavior.     

Perception of safe robot speed in virtual and real industrial environments

The purpose of this project was to study the influences of dynamic virtual objects in an Internet‐based virtual industrial environment. The main objectives of this study were to investigate perception of safe robot speed and perception of acceptability. Virtual industrial environments were designed and developed to conduct the experiment. The hypotheses specifying the relationships between perceptions of the robot size, type, different robot starting speed conditions, and gender were tested through data collected from 32 participants. The results indicated that the perception of safe speed was significantly different depending on robot sizes and the initial robot speed conditions. This was consistent with results shown in previous literature for tests in a real industrial environment. © 2006 Wiley Periodicals, Inc. Hum Factors Man 16: 369–383, 2006.     

NeTra: A toolbox for navigating large image databases

We present here an implementation of NeTra, a prototype image retrieval system that uses color, texture, shape and spatial location information in segmented image regions to search and retrieve similar regions from the database. A distinguishing aspect of this system is its incorporation of a robust automated image segmentation algorithm that allows object- or region-based search. Image segmentation significantly improves the quality of image retrieval when images contain multiple complex objects. Images are segmented into homogeneous regions at the time of ingest into the database, and image attributes that represent each of these regions are computed. In addition to image segmentation, other important components of the system include an efficient color representation, and indexing of color, texture, and shape features for fast search and retrieval. This representation allows the user to compose interesting queries such as “retrieve all images that contain regions that have the color of object A, texture of object B, shape of object C, and lie in the upper of the image”, where the individual objects could be regions belonging to different images. A Java-based web implementation of NeTra is available at http://vivaldi.ece.ucsb.edu/Netra.     

VU-flow: a visualization tool for analyzing navigation in virtual environments

This paper presents a tool for the visual analysis of navigation patterns of moving entities, such as users, virtual characters or vehicles in 3D virtual environments (VEs). The tool, called VU-Flow, provides a set of interactive visualizations that highlight interesting navigation behaviors of single or groups of moving entities that were the VE together or separately. The visualizations help to improve the design of VEs and to study the navigation behavior of users, e.g., during controlled experiments. Besides VEs, the proposed techniques could also be applied to visualize real-world data recorded by positioning systems, allowing one to employ VU-Flow in domains such as urban planning, transportation, and emergency response     

Storytelling in virtual environments from a virtual guide perspective

This paper describes our proposal for storytelling in virtual environments from a virtual guide perspective, detailing the involved knowledge representation and algorithms. In our model the guide begins at a particular location and starts to navigate the world telling the user stories related to the places she visits. Our guide tries to emulate a real guides behaviour in such a situation. In particular, she behaves as a spontaneous real guide who knows stories about the places in the virtual world but has not prepared an exhaustive tour nor a storyline.