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Results for “virtual environment”

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At least 127 records · Page 7Linked to original sources

PubMed1997

Modeling mechanical cardiopulmonary interactions for virtual environments.

We have developed a computer system for modeling mechanical cardiopulmonary behavior in an interactive, 3D virtual environment. The system consists of a compact, scalar description of cardiopulmonary mechanics, with an emphasis on respiratory mechanics, that drives deformable 3D anatomy to simulate mechanical behaviors of and interactions between physiological systems. Such an environment can be used to facilitate exploration of cardiopulmonary physiology, particularly in situations that are difficult to reproduce clinically. We integrate 3D deformable body dynamics with new, formal models of (scalar) cardiorespiratory physiology, associating the scalar physiological variables and parameters with corresponding 3D anatomy. Our approach is amenable to modeling patient-specific circumstances in two ways. First, using CT scan data, we apply semi-automatic methods for extracting and reconstructing the anatomy to use in our simulations. Second, our scalar models are defined in terms of clinically-measurable, patient-specific parameters. This paper describes our approach and presents a sample of results showing normal breathing and acute effects of pneumothoraces.

Computer Simulation↗

PubMed2004

Factors that influence presence in educational virtual environments.

The present article is a part of a project for the measurement of presence in educational virtual environments (VEs), since presence is correlated with higher levels of cognitive performance and emotional development, factors that contribute to knowledge construction. The aim of our study was to investigate the sense of presence of 12-year-old pupils within an educational VE representing an ancient Greek house through a sense of embodiment and the ability to handle task performance, while using various peripheral devices. This is the first report on presence measurement with children, based on the indication that children and adults may apply very unrelated criteria. Our results showed statistically significant differences on the level of tiredness and ease of use in using six different input devices. The combination of the keyboard and mouse and the keyboard on its own were the least tedious and easiest input devices, giving a sense of presence as stated by the pupils. Environmental richness and the high level of interactivity within the VE resulted in a high degree of presence for almost all the pupils. The majority of them felt a sense of presence whilst driving the avatar, indicating that presence is significantly correlated with pupils' degree of association with their virtual bodies. All the pupils felt a sense of presence when wearing the head-mounted display. Our findings are in line with those of other researchers and show evidence of personal, social and environmental presence.

Association Learning↗

PubMed1999

Oculomotor changes within virtual environments.

This paper discusses the oculomotor changes which might be expected to occur during immersion in a virtual environment whilst wearing a Head mounted display (HMD). To do so, it first examines the stimulus presented to the eyes, and then considers how this stimulus could affect the visual system. Theoretical analysis and empirical results from the use of three different HMDs point towards the same conclusion, that in this context a mismatch between the instrument inter-ocular distance (IOD) and the user's inter-pupillary distance is of little concern, unlike the mismatch between the instrument IOD and the inter-screen distance.

Adaptation, Physiological↗

PubMed1999

Physical ergonomics of virtual environment use.

This paper describes an investigation of the types of problems that may be experienced by Virtual Reality (VR) users. Initial concerns have been voiced about various issues concerning the design of VR equipment, particularly the physical ergonomics of head-mounted displays (HMDs) and hand-held input devices, and the problems associated with display resolution and lags. This study investigated a number of VR users' perceptions of the types of physical ergonomics issues that they were aware of when participating in a number of different virtual environments (VEs), using different VR systems. Several different methods were employed, including questionnaires, body mapping, user observation and interviews. Issues highlighted as either causing participants discomfort or interfering with their experience of the VE were: discomfort from static posture requirements, general discomfort from wearing the HMD, difficulty becoming accustomed to 3D hand held input devices, dissatisfaction with deficits in the visual display and fear of getting 'tangled' in connecting cables. The implications of these findings for developers, implementers and users of VR are discussed.

Adult↗

PubMed2005

Exploring virtual environments with an EEG-based BCI through motor imagery.

In this paper, we describe the possibility of navigating in a virtual environment using the output signal of an EEG-based Brain-Computer Interface (BCI). The graphical capabilities of virtual reality (VR) should help to create new BCI-paradigms and improve feedback presentation. The objective of this combination is to enhance the subject's learning process of gaining control of the BCI. In this study, the participant had to imagine left or right hand movements while exploring a virtual conference room. By imaging a left hand movement the subject turned virtually to the left inside the room and with right hand imagery to the right. In fact, three trained subjects reached 80% to 100% BCI classification accuracy in the course of the experimental sessions. All subjects were able to achieve a rotation in the VR to the left or right by approximately 45 degrees during one trial.

Adult↗

PubMed2001

A virtual environment for simulated rat dissection.

Animal dissection for the scientific examination of organ subsystems is a delicate procedure. Performing this procedure under the complex environment of microgravity presents additional challenges because of the limited training opportunities available that can recreate the altered gravity environment. Traditional crew training often occurs several months in advance of experimentation, provides limited realism, and involves complicated logistics. We have developed an interactive virtual environment that can simulate several common tasks performed during animal dissection. In this paper, we describe the imaging modality used to reconstruct the rat in virtual space, provide an overview of the simulation environment and briefly discuss some of the techniques used to manipulate the virtual rat.

Animals↗

PubMed1998

Task performance in virtual environments used for cognitive rehabilitation after traumatic brain injury.

OBJECTIVE: This report describes a reliability study using a prototype computer-simulated virtual environment to assess basic daily living skills in a sample of persons with traumatic brain injury (TBI). The benefits of using virtual reality in training for situations where safety is a factor have been established in defense and industry, but have not been demonstrated in rehabilitation. SUBJECTS: Thirty subjects with TBI receiving comprehensive rehabilitation services at a residential facility. METHODS: An immersive virtual kitchen was developed in which a meal preparation task involving multiple steps could be performed. The prototype was tested using subjects who completed the task twice within 7 days. RESULTS: The stability of performance was estimated using intraclass correlation coefficients (ICCs). The ICC value for total performance based on all steps involved in the meal preparation task was .73. When three items with low variance were removed the ICC improved to .81. Little evidence of vestibular optical side-effects was noted in the subjects tested. CONCLUSION: Adequate initial reliability exists to continue development of the environment as an assessment and training prototype for persons with brain injury.

Activities of Daily Living↗

PubMedDate not supplied

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.

Algorithms↗

PubMed1997

Basic technology of simulation system for laparoscopic surgery in virtual environment with force display.

A basic simulation system for laparoscopic surgery was constructed. The system consists of force display in a virtual environment construction system. Recently, laparoscopic surgery has become popular around the world. However, this operation strategy requires very high dexterity, so that only some medical doctors can use it. Doctors can see the human organs in a three-dimensional environment in the case of ordinary operations. On the other hand, in the case of laparoscopic surgery, doctors can only see a narrow space in a two-dimensional environment on a CRT monitor and tactile information is decreased during operation procedures. We therefore developed a basic technology of surgical simulator for laparoscopic surgery. The focus of our research is the presentation of resistance from virtual organs.

Computer Simulation↗

PubMed1999

A preliminary investigation into the use of virtual environments in memory retraining after vascular brain injury: indications for future strategy?

PURPOSE: In a preliminary investigation of the use of Virtual Environments (VEs) in neurorehabilitation, this study compares the effects of active and passive experience of a VE on two types of memory in vascular brain injury patients and controls. METHOD: Forty-eight patients with vascular brain injury and 48 non-impaired control participants were randomly assigned to active and passive VE conditions. The active participants explored a virtual bungalow seeking a particular object; the passive participants observed, but did not control movement through the VE, also seeking the object. Afterwards, both active and passive participants completed spatial recognition and object recognition tests. RESULTS: Expectedly, the patients were impaired relative to the controls but were able to perform the virtual tasks. Active participation in the VE enhanced memory for its spatial layout in both patients and controls. On object recognition, active and passive patients performed similarly, but passive controls performed better than active controls. CONCLUSIONS: The findings are discussed in relation to their implications for memory rehabilitation strategies.

Adult↗

PubMed2003

Identification of metaphors for virtual environment training systems.

The objective of this effort was to develop potential metaphors for assisting wayfinding and navigation in current virtual environment (VE) training systems. Although VE purports a number of advantages over traditional, full-scale simulator training devices (deployability, footprint, cost, maintainability, scalability, networking), little design guidance exists beyond individual instantiations with specific platforms. A review of metaphors commonly incorporated into human-computer interactive systems indicated that existing metaphors have largely been used as orientation aids, mainly in the form of guided navigational assistance, with some position guidance. Advanced metaphor design concepts were identified that would not only provide trainees with a useful orienting framework but also enhance visual access and help differentiate an environment. The effectiveness of these concepts to aid navigation and wayfinding in VEs must be empirically validated.

Computer Simulation↗

PubMedDate not supplied

Ribbon networks for modeling navigable paths of autonomous agents in virtual environments.

This paper presents the Environment Description Framework (EDF) for modeling complex networks of intersecting roads and pathways in virtual environments. EDF represents information about the layout of streets and sidewalks, the rules that govern behavior on roads and walkways, and the locations of agents with respect to navigable structures. The framework serves as the substrate on which behavior programs for autonomous vehicles and pedestrians are built. Pathways are modeled as ribbons in space. The ribbon structure provides a natural coordinate frame for defining the local geometry of navigable surfaces. EDF includes a powerful runtime interface supported by robust and efficient code for locating objects on the ribbon network, for mapping between Cartesian and ribbon coordinates, and for determining behavioral constraints imposed by the environment.

Algorithms↗

PubMed2007

Using virtual environments for teaching social understanding to 6 adolescents with autistic spectrum disorders.

Six teenagers with Autistic Spectrum Disorders (ASDs) experienced a Virtual Environment (VE) of a café. They also watched three sets of videos of real cafés and buses and judged where they would sit and explained why. Half of the participants received their VE experience between the first and second sets of videos, and half experienced it between the second and third. Ten naïve raters independently coded participants' judgments and reasoning. In direct relation to the timing of VE use, there were several instances of significant improvement in judgments and explanations about where to sit, both in a video of a café and a bus. The results demonstrate the potential of Virtual Reality for teaching social skills.

Adolescent↗

PubMed1997

Development of a virtual sand box: an application of virtual environment for psychological treatment.

The sand play technique has often been used in psychological treatments or in the diagnosis of autism patients. In this paper, the prototype application called "virtual sand box" is developed as a virtual environment to support this technique. Experimental results show the advantages of applying virtual reality technology to clinical medicine; particularly with respect to the diagnosis of people with psychological and psychiatrical difficulties such as autism and neurosis. The actual system has been implemented by using a graphics workstation, a wide-view field display, and 3D input devices.

Autistic Disorder↗

PubMed2005

Effects of increasing visual load on aurally and visually guided target acquisition in a virtual environment.

The aim of the present study is to investigate interactions between vision and audition during a target acquisition task performed in a virtual environment. We measured the time taken to locate a visual target (acquisition time) signalled by auditory and/or visual cues in conditions of variable visual load. Visual load was increased by introducing a secondary visual task. The auditory cue was constructed using virtual three-dimensional (3D) sound techniques. The visual cue was constructed in the form of a 3D updating arrow. The results suggested that both auditory and visual cues reduced acquisition time as compared to an uncued condition. Whereas the visual cue elicited faster acquisition time than the auditory cue, the combination of the two cues produced the fastest acquisition time. The introduction of secondary visual task differentially affected acquisition time depending on cue modality. In conditions of high visual load, acquiring a target signalled by the auditory cue led to slower and more error-prone performance than acquiring a target signalled by either the visual cue alone or by both the visual and auditory cues.

Adolescent↗

PubMed1998

Personal stories within virtual environments: embodiments of a model for cancer patient information software.

Two new cancer patient information CD-ROMs extend the personal stories within virtual environments model of cancer patient information developed for Breast Cancer Lighthouse. Cancer Pain Retreat and Cancer Prevention Park: Games for Life are intended to inform and inspire users in an emotionally calming and intimately informative manner. The software offers users an experience--of visiting a virtual place and meeting and talking with patients and health care professionals.

CD-ROM↗

PubMed1998

Empirical models based on free-modulus magnitude estimation of perceived presence in virtual environments.

A series of 3 studies was conducted to test free-modulus magnitude estimation as a measure of perceived presence in virtual environments (VEs) and to model the first- and second-order effects of 11 VE system parameters on perceived presence across 5 subtasks. Sequential experimentation techniques were used to build 4 empirical models using polynomial regression. An integrated empirical model of data combined across 2 experiments demonstrated that all significant factors had a positive effect on perceived presence. Three of these parameters--field of view, sound, and head tracking--had almost 3 times as much influence on presence than the other 4 significant parameters, which were visual display resolution, texture mapping, stereopsis, and scene update rate. Sequential experimentation was an efficient tool for building empirical models of perceived presence, but the subjective nature of this phenomenon and individual differences made data bridging across sequential studies problematic. It was concluded that magnitude estimation is a useful measure of perceived presence, and the resulting polynomial regression models can be used to facilitate VE system design decisions. This research has broad application in the selection and design of VE system components and overall design of VE systems.

Adolescent↗

PubMedDate not supplied

Control of virtual environments for young people with learning difficulties.

PURPOSE: The objective of this research is to identify the requirements for the selection or development of usable virtual environment (VE) interface devices for young people with learning disabilities. METHOD: A user-centred design methodology was employed, to produce a design specification for usable VE interface devices. Details of the users' cognitive, physical and perceptual abilities were obtained through observation and normative assessment tests. CONCLUSIONS: A review of computer interface technology, including virtual reality and assistive devices, was conducted. As there were no devices identified that met all the requirements of the design specification, it was concluded that there is a need for the design and development of new concepts. Future research will involve concept and prototype development and user-based evaluation of the prototypes.

Adolescent↗