**2. Applications of virtual environments**

The use of virtual environments in real life applications has grown tremendously in the last decade. A growing number of educators and researchers are reported to have found virtual environments useful for teaching and research, despite its challenging technical requirements. Many of the properties of virtual environments are viewed to be conducive for good learning as they tend to be interactive, engaging, and provide safe places for students to learn by doing and experimentation. There is also ample provision of scaffolding and immediate feedback to measure if learning has actually taken place. The report reveals that over 74 universities and colleges already have a presence (virtual campuses) within Second Life, an online virtual world created by Linden Lab, where a host of client programs (Viewers) enable Users (Residents) to interact with one another through avatars. The Residents can explore the virtual world, meet other Residents, socialize, participate in individual or group activities, trade virtual property and services with each other. Second Life, taunted as the Internet's largest user-created 3D virtual world community, has been used for distance learning, museum-style exhibits, corporate training, broadcasting information, or simply as an interactive supplement to traditional classroom environments. It is envisaged that virtual classes and virtual classrooms will become more commonplace, as the number of schools that hold online classes within Second Life continues to grow. As simulations and designed experiences, , researchers believe that virtual worlds are useful for experiential, exploratory learning and for teaching various content areas like business (e.g. virtual real estate, intellectual property), economics, art design and architecture, science, among other topics. It is also reported that Second Life already has over a million active users.

In the use for therapeutic applications, the field of motor rehabilitation, especially after a stroke assault, is one of the fields that have benefitted significantly from virtual environments applications. A number of virtual environment-based systems have been developed along the theory underlying neuronal mechanism targeting recovery. It is assumed that recovery could be facilitated by harnessing mechanisms underlying neuronal reorganization. O'Sullivan and Schmitz (2001) argued that motor recovery evolves from a complex set of neurological and mechanical processes that inform postures and that the brain normally provides signal that help with balance, coordination and orientation necessary for movements, especially walking. Molnar (2002) argued that stroke impairs

In another view, some researchers like Strickland, Hodges, North and Weghorst (1997) describe virtual environments as computer presence and feel of another place with tracking of what the person does in this imaginary scene. They argued that when the headsets are used to remove the real background of the user, the mind is fooled and the senses are made to accept as reality this new imaginary environment. Some simulations of virtual environments add more sensory information to depict the imaginary world as close to reality as possible and advanced haptic systems are now being coupled with tactile information (force feedback) to create systems for medical and gaming applications. Advances in telecommunications have enabled remote communication environments which now provide virtual presence of users with the concepts of telepresence and telexistence (Liang et al., 2006; Szigeti et al., 2009). The example above demonstrates the use of virtual environment in parachute training. The system provides a parachute simulation where students learn how to control flight movements

The use of virtual environments in real life applications has grown tremendously in the last decade. A growing number of educators and researchers are reported to have found virtual environments useful for teaching and research, despite its challenging technical requirements. Many of the properties of virtual environments are viewed to be conducive for good learning as they tend to be interactive, engaging, and provide safe places for students to learn by doing and experimentation. There is also ample provision of scaffolding and immediate feedback to measure if learning has actually taken place. The report reveals that over 74 universities and colleges already have a presence (virtual campuses) within Second Life, an online virtual world created by Linden Lab, where a host of client programs (Viewers) enable Users (Residents) to interact with one another through avatars. The Residents can explore the virtual world, meet other Residents, socialize, participate in individual or group activities, trade virtual property and services with each other. Second Life, taunted as the Internet's largest user-created 3D virtual world community, has been used for distance learning, museum-style exhibits, corporate training, broadcasting information, or simply as an interactive supplement to traditional classroom environments. It is envisaged that virtual classes and virtual classrooms will become more commonplace, as the number of schools that hold online classes within Second Life continues to grow. As simulations and designed experiences, , researchers believe that virtual worlds are useful for experiential, exploratory learning and for teaching various content areas like business (e.g. virtual real estate, intellectual property), economics, art design and architecture, science, among other

topics. It is also reported that Second Life already has over a million active users.

In the use for therapeutic applications, the field of motor rehabilitation, especially after a stroke assault, is one of the fields that have benefitted significantly from virtual environments applications. A number of virtual environment-based systems have been developed along the theory underlying neuronal mechanism targeting recovery. It is assumed that recovery could be facilitated by harnessing mechanisms underlying neuronal reorganization. O'Sullivan and Schmitz (2001) argued that motor recovery evolves from a complex set of neurological and mechanical processes that inform postures and that the brain normally provides signal that help with balance, coordination and orientation necessary for movements, especially walking. Molnar (2002) argued that stroke impairs

through a series of computer-generated scenarios.

**2. Applications of virtual environments** 

these complex set of processes involved in walking. Liepert and his colleagues in 2000 along with Jack and his fellow researchers in 2001 showed indications that virtual environments can be used to simulate artificial images that trigger biofeedback mechanisms that can aid in motor recovery.

In the work of Jack and his colleagues (Jack et al., 2001), a PC-based desktop system was developed that employed virtual environments for rehabilitating the hand function in stroke patients. The system uses two input devices, a CyberGlove and a Rutgers Master II-ND (RMII) force feedback glove, that allow users to interact with the virtual environment. The virtual environment presents four rehabilitation routines, each designed to exercise one specific parameter of hand movement e.g., range of motion. The authors used performancebased target levels to encourage patients to use the system and to individualize exercise difficulty based on the patient's specific need. Three chronic stroke patients were employed to carry out pilot clinical trials of the system daily for two weeks. Objective evaluations revealed that each patient showed improvement on most of the hand parameters over the course of the training.

In 2002, Boian and his colleagues used a similar virtual environment in a different context to rehabilitate four post-stroke patients in the chronic phase. The system developed was distributed over three sites (rehabilitation site, data storage site, and data access site) and connected to each other through the Internet. At the rehabilitation site, the patients underwent upper-extremity therapy using a CyberGlove and a Rutgers Master II (RMII) haptic glove integrated with PC-based system that provides the virtual environment. The patients interacted with the system using the sensing gloves, and feedback was given on the computer screen. The data storage site hosted the main server for the system. It had an Oracle database, a monitoring server, and a web site for access to the data. The data access site was a 'place-independent' site, being any computer with Internet access. The therapist or physician could access the patients' data remotely from any location with Internet connections. The patients exercised for about two hours per day, five days a week for three weeks, within the virtual environment to reduce impairments in their finger range of motion, speed, fractionation and strength. Results showed that three of the four patients had improvements in their thumbs' range of motion and finger speed over the three-week trial while all the patients had significant improvements in finger fractionation, and modest gains in finger strength.

Similarly, in the same year, Alma S. Merians, with some members of Boian's research group continued related work using the CyberGlove and the RMII glove, coupled with virtual reality technology, to create an interactive, motivating virtual environment in which practice intensity and feedback were manipulated to present individualized treatments to retrain movements in three patients who were in the chronic phase following stroke. The patients participated in a two-week training program, spending about three-and-half hours per day on dexterity tasks using real objects and virtual reality exercises. The virtual reality simulations were targeted for upper-extremity improvements in range of motion, movement speed, fractionation, and force productions. Results showed that one of the three patients, the most impaired at the beginning of the intervention, gained improvement in the thumb and fingers in terms of range of motion and speed of movement. Another patient improved in fractionation and range of motion of his thumb and fingers. The third patient made the greatest gains as that patient was reported to have gained improvements in the range of motion and strength of the thumb, velocity of the thumb and fingers, and fractionation.

Virtual Environments in Physical Therapy 5

This is a headset used for full immersion. It can contain a pair of goggles or a full helmet. In front of the eyes are two tiny monitors that present images in three dimensions. Most HMDs include a head tracker so that the system can respond to head movements. The small monitors placed in front of each eye provide stereo, bi-ocular or monocular images. The Stereo images come in a similar way to shutter glasses as only a slightly different image is presented to each eye. The major difference is that the two screens are placed very close (50- 70mm) to the eye, while the HMD optical system keeps the image which the wearer focuses on much further away. Bi-ocular images can present identical images on each screen while

The most commonly used HMDs employ small Liquid Crystal Display (LCD) panels which provides enough screen resolution for many applications, but the more expensive ones employ Cathode Ray Tubes (CRT) that increase the resolution of the screen image. Fully immersive systems usually exclude the user's view of the real world and enhance the field of view of the computer generated world. The advantage of this method is that the user is provided with a 360° field of regard giving them a visual image in whatever direction they turn their head. The HMDs are central to achieving the sense of full immersion; hence their resolution, the update rate, and contrast and illumination of the display are critical factors.

**3.1.1 Head Mounted Display (HMD)** 

Fig. 2. Virtual Reality Headsets

**3.2 Non-immersive environments or desktop systems** 

These are the least immersive implementation of virtual simulation techniques. With Personal Computers on the desks, the virtual environment is created through a portal or

monocular images are formed using only one display screen.

These evidences showed the usefulness of virtual environments for rehabilitation therapy to improve movement performance and/or functional ability and add to other research efforts such as the study of computerized training in a virtual reality environment as an enhancement to existing methods of retraining the hand in patients in the later phase of recovery after a stroke (Merians et al., 2002), robot training using a virtual environment to enhance stroke rehabilitation (Krebs, Hogan, Aisen & Volpe, 1998), and Professor Baram's work on a virtual reality device that helps Parkinson's and stroke patients walk better (Garbi, 2002). Curtis (1998) and Merians et al. (2002) observed that the field of virtual reality was still in its infancy, especially for special needs; however, crossovers with fields such as computer graphics, Computer-Aided Design (CAD), acoustics, and human-computer interface, which are much better established, are currently making the creation of virtual environments more viable. Advances in technology, in terms of computer processing power and graphics hardware, have made it possible to create virtual environment on cheap computer platforms (e.g., 486 or Pentium IBM compatible PCs). These were previously only possible on high-end workstations such as silicon graphics machines. Breakthroughs in LCD technology are already being delivered in the form of cheaper and higher resolution virtual reality headsets, which are required for fully-immersive virtual environment. Global Positioning Satellite (GPS) technologies, such as compact gyroscopes, promise mass production of three-dimensional (3D) input devices, similar to those already found in the Phillips 3D mouse, to facilitate interactions at a very low cost, and fields such as Human Computer Interaction (HCI) have long been focused on the use of virtual reality as an alternative means of interaction (Snowdon, West & Howard, 1993). Telecommunication networks currently can deliver via the Internet high bandwidth graphical information required by virtual reality, and technology solutions are now being implemented using virtual reality for special needs (Boian et al. 2002; Smythe, Furner & Mercinelli, 1995). Web page designs can now utilize 3D capabilities using the Virtual Reality Mark-up Language (VRML), and the ability to extend healthcare's reach has been advocated (Plant, 1996).

#### **3. Forms of virtual environments**

Virtual environments are generally classified by the degree of immersion it provides through level of user interactivity, image complexity, stereoscopic view, field of regard and the update rate of display. A careful and complex combination of all these factors determine the level of immersion achieved as no one parameter is effective in itself.

#### **3.1 Fully immersive environments**

Virtual Environment can be fully immersive, where, in this sense, the user feels they are part of the simulated world. All the senses of the user are engaged, sight, sound, touch, smell, taste, with technology such as panoramic 3D displays for full sense of vision, surround sounds for auditory immersion, haptic and force feedback for tactile feelings, and smell and taste replications for olfactory and gustation experiences. This form of environment. Fully immersive environments provide the most direct experience of virtual environments and have been reported to be probably the most widely known VR implementation where the user either wears a Head Mounted Display (HMD) or uses some form of head-coupled display such as a Binocular Omni-Orientation Monitor or BOOM (Bolas, 1994).

These evidences showed the usefulness of virtual environments for rehabilitation therapy to improve movement performance and/or functional ability and add to other research efforts such as the study of computerized training in a virtual reality environment as an enhancement to existing methods of retraining the hand in patients in the later phase of recovery after a stroke (Merians et al., 2002), robot training using a virtual environment to enhance stroke rehabilitation (Krebs, Hogan, Aisen & Volpe, 1998), and Professor Baram's work on a virtual reality device that helps Parkinson's and stroke patients walk better (Garbi, 2002). Curtis (1998) and Merians et al. (2002) observed that the field of virtual reality was still in its infancy, especially for special needs; however, crossovers with fields such as computer graphics, Computer-Aided Design (CAD), acoustics, and human-computer interface, which are much better established, are currently making the creation of virtual environments more viable. Advances in technology, in terms of computer processing power and graphics hardware, have made it possible to create virtual environment on cheap computer platforms (e.g., 486 or Pentium IBM compatible PCs). These were previously only possible on high-end workstations such as silicon graphics machines. Breakthroughs in LCD technology are already being delivered in the form of cheaper and higher resolution virtual reality headsets, which are required for fully-immersive virtual environment. Global Positioning Satellite (GPS) technologies, such as compact gyroscopes, promise mass production of three-dimensional (3D) input devices, similar to those already found in the Phillips 3D mouse, to facilitate interactions at a very low cost, and fields such as Human Computer Interaction (HCI) have long been focused on the use of virtual reality as an alternative means of interaction (Snowdon, West & Howard, 1993). Telecommunication networks currently can deliver via the Internet high bandwidth graphical information required by virtual reality, and technology solutions are now being implemented using virtual reality for special needs (Boian et al. 2002; Smythe, Furner & Mercinelli, 1995). Web page designs can now utilize 3D capabilities using the Virtual Reality Mark-up Language (VRML), and the ability to extend healthcare's reach has been advocated (Plant, 1996).

Virtual environments are generally classified by the degree of immersion it provides through level of user interactivity, image complexity, stereoscopic view, field of regard and the update rate of display. A careful and complex combination of all these factors determine

Virtual Environment can be fully immersive, where, in this sense, the user feels they are part of the simulated world. All the senses of the user are engaged, sight, sound, touch, smell, taste, with technology such as panoramic 3D displays for full sense of vision, surround sounds for auditory immersion, haptic and force feedback for tactile feelings, and smell and taste replications for olfactory and gustation experiences. This form of environment. Fully immersive environments provide the most direct experience of virtual environments and have been reported to be probably the most widely known VR implementation where the user either wears a Head Mounted Display (HMD) or uses some form of head-coupled

the level of immersion achieved as no one parameter is effective in itself.

display such as a Binocular Omni-Orientation Monitor or BOOM (Bolas, 1994).

**3. Forms of virtual environments** 

**3.1 Fully immersive environments** 

#### **3.1.1 Head Mounted Display (HMD)**

This is a headset used for full immersion. It can contain a pair of goggles or a full helmet. In front of the eyes are two tiny monitors that present images in three dimensions. Most HMDs include a head tracker so that the system can respond to head movements. The small monitors placed in front of each eye provide stereo, bi-ocular or monocular images. The Stereo images come in a similar way to shutter glasses as only a slightly different image is presented to each eye. The major difference is that the two screens are placed very close (50- 70mm) to the eye, while the HMD optical system keeps the image which the wearer focuses on much further away. Bi-ocular images can present identical images on each screen while monocular images are formed using only one display screen.

The most commonly used HMDs employ small Liquid Crystal Display (LCD) panels which provides enough screen resolution for many applications, but the more expensive ones employ Cathode Ray Tubes (CRT) that increase the resolution of the screen image. Fully immersive systems usually exclude the user's view of the real world and enhance the field of view of the computer generated world. The advantage of this method is that the user is provided with a 360° field of regard giving them a visual image in whatever direction they turn their head. The HMDs are central to achieving the sense of full immersion; hence their resolution, the update rate, and contrast and illumination of the display are critical factors.

#### Fig. 2. Virtual Reality Headsets

#### **3.2 Non-immersive environments or desktop systems**

These are the least immersive implementation of virtual simulation techniques. With Personal Computers on the desks, the virtual environment is created through a portal or

Virtual Environments in Physical Therapy 7

observer must see slightly different images of the scene under regard in each eye. In the real world this occurs because the two eyes are placed slightly apart in the head, and so each eye views the scene from a slightly different position. Multi-user issues have been reported as one of the main advantages of these systems and designers must consider the handover of

Virtual environments applications continue to grow. Developers are coming out with new technologies that can simulate effects such as wind, vibration and lightning to enrich the virtual environment for a true model of reality. Virtual environments are being successfully used for applications such as driving and flight simulators and we are now witnessing some entertainment environment like the simulated Viruga Mountains in Rwanda to explore a

Despite all the strides in virtual environment applications, research still shows inconsistencies in the reports on research efforts in virtual environments. One main contention is whether skills gained in virtual environments transfer to real-world conditions. This argument has come to the forefront in the widely use of virtual environment for therapeutic applications. For example, efforts to promote functional recovery through therapeutic interventions like neurofacilitation techniques, progressive strengthening, biofeedback and electrical simulation, after the occurrence of stroke, have yielded inconsistent results (Duncan, 1997; Feys et al., 1998; Merians et al., 2002; Richards & Pohl, 1999). O'Sullivan and Schmitz (1994) argued that these inconsistencies stemmed from inadequate training and skills in performing these procedures in order to ensure the validity and reliability of the tests. Wilson, Foreman and Tlauka (1996) reported that internal representations resulting from exploration of simulated space transferred to the real environment. Kozak et al. (1993), Deutsch, Latonio, Burdea and Boian (2001), argued that although subjects trained on a motor task in a virtual environment demonstrated the ability to improve performance in that environment, the learning did not always transfer to the real-world task. Jack et al. (2001) attributed this problem to the current paucity of investigation into the use of VR for motor skill training. These inconsistencies indicate that research in motor task training and transfer of that task to the real-world environment is neither fully understood nor entirely conclusive (Jack et al., 2001). These conflicting findings need to be more carefully explored in order to ascertain the usefulness of VR as an enhancement to traditional therapy. Fox and Fried-Oken (1996) also observed that many questions relating to the generalization of new learning to the natural environment

Recent studies have shown that virtual reality technology can be used to provide this treatment approach based on its capability to create an integrated, interactive, motivating environment in which practice intensity and feedback can be manipulated to effect functional recovery or improvements in patients following stroke (Liepert et al., 2000;

The author conducted a case study to justify his own belief on this inconclusive subject. The research undertaken also aims to justify or not research efforts in virtual environments

**4. Some barriers and issues in virtual environment applications** 

control between users as this technology develops.

tribe of Mountain Gorillas.

remained largely unanswered.

Merians et al., 2002; Taub, Uswatte & Pidikiti, 1999;).

**5. A virtual environment case study** 

window by utilising a standard high resolution monitor. Users interact with the environment through conventional means such as keyboards, mice and trackballs, which can be augmented by using 3D interaction devices such as a SpaceBallä or DataGloveä.

The non-immersive systems are more economical to set up as they usually do not require the highest level of graphics performance and without any specialized hardware requirements. They can also be cloned on high specification Personal Computers. These are the lowest cost VR solutions that are being employed for many virtual environment applications. The reported drawback, however, is that they are usually outperformed by the more sophisticated systems. They are confined within the limit of the existing 2D interaction device and thus provide little or no sense of immersion hence of little use where the perception of scale is an important factor. It is expected that the growing use of Virtual Reality Modelling Reality Language (VRML), which is also being adopted as a de-facto standard for the transfer of 3D model data and virtual worlds via the internet, should fuel the use of non-immersive virtual environment applications. It is argued that the advantage of VRML is in its ability to run relatively well on personal computers as opposed to many other proprietary VR authoring tools and the growth in its use that can result in the current trends of commercial VR software having VRML as a tool incorporated in them to explore the commercial possibilities of desktop VR applications.

#### **3.3 Semi-immersive virtual environments**

In semi-immersive virtual environments, the viewer becomes partly but not fully immersed in this environment. These systems borrowed considerably from technologies developed in the flight simulation field and are a relatively new implementation of VR technology, which often consists of a large, concave screen, projection system and monitor similar to the large screen experiences seen at IMAX cinemas. They usually involve high end computer graphics. A flight simulator, for an example may present a semi-immersive simulation of an aircraft cockpit where the set up would consist of a physical display of the cockpit and chair with three dimensional images. The trainee does not need to wear virtual reality gear such as a data glove or head mounted display (HMD) and is still aware of the real world outside of the virtual environment. Semi-immersive systems present a few advantages over fully immersive systems such as a CAVE, an automatic virtual environment system, which includes cost, ease of use and logistics. But it has its disadvantages as well which include limited range of interaction devices and problems with multi-user applications

A semi-immersive system can be set up with a relatively high performance graphics computing system which can be coupled with a large screen monitor, a large screen projector system or a multiple television projection systems. They provide a greater sense of presence than non-immersive systems and also a greater appreciation of scale. Because the images can be of a far greater resolution than those of HMDs, semi-immersive systems possess the ability to share the virtual experience. This has been argued to be its advantage, especially in educational applications as it allows simultaneous experience of the virtual environment without the need for head-mounted immersive systems. Also, stereographic imaging can be achieved, using some type of shuttered glasses in synchronisation with the graphics system. According to vrs.org, Shutter Glasses are Liquid Crystal Shutter (LCS) glasses which consist of a lightweight headset with a liquid crystal lens placed over each eye. Stereopsis works on the principle that in order to perceive depth in a scene, the

window by utilising a standard high resolution monitor. Users interact with the environment through conventional means such as keyboards, mice and trackballs, which can be augmented by using 3D interaction devices such as a SpaceBallä or DataGloveä.

The non-immersive systems are more economical to set up as they usually do not require the highest level of graphics performance and without any specialized hardware requirements. They can also be cloned on high specification Personal Computers. These are the lowest cost VR solutions that are being employed for many virtual environment applications. The reported drawback, however, is that they are usually outperformed by the more sophisticated systems. They are confined within the limit of the existing 2D interaction device and thus provide little or no sense of immersion hence of little use where the perception of scale is an important factor. It is expected that the growing use of Virtual Reality Modelling Reality Language (VRML), which is also being adopted as a de-facto standard for the transfer of 3D model data and virtual worlds via the internet, should fuel the use of non-immersive virtual environment applications. It is argued that the advantage of VRML is in its ability to run relatively well on personal computers as opposed to many other proprietary VR authoring tools and the growth in its use that can result in the current trends of commercial VR software having VRML as a tool incorporated in them to explore

In semi-immersive virtual environments, the viewer becomes partly but not fully immersed in this environment. These systems borrowed considerably from technologies developed in the flight simulation field and are a relatively new implementation of VR technology, which often consists of a large, concave screen, projection system and monitor similar to the large screen experiences seen at IMAX cinemas. They usually involve high end computer graphics. A flight simulator, for an example may present a semi-immersive simulation of an aircraft cockpit where the set up would consist of a physical display of the cockpit and chair with three dimensional images. The trainee does not need to wear virtual reality gear such as a data glove or head mounted display (HMD) and is still aware of the real world outside of the virtual environment. Semi-immersive systems present a few advantages over fully immersive systems such as a CAVE, an automatic virtual environment system, which includes cost, ease of use and logistics. But it has its disadvantages as well which include

limited range of interaction devices and problems with multi-user applications

A semi-immersive system can be set up with a relatively high performance graphics computing system which can be coupled with a large screen monitor, a large screen projector system or a multiple television projection systems. They provide a greater sense of presence than non-immersive systems and also a greater appreciation of scale. Because the images can be of a far greater resolution than those of HMDs, semi-immersive systems possess the ability to share the virtual experience. This has been argued to be its advantage, especially in educational applications as it allows simultaneous experience of the virtual environment without the need for head-mounted immersive systems. Also, stereographic imaging can be achieved, using some type of shuttered glasses in synchronisation with the graphics system. According to vrs.org, Shutter Glasses are Liquid Crystal Shutter (LCS) glasses which consist of a lightweight headset with a liquid crystal lens placed over each eye. Stereopsis works on the principle that in order to perceive depth in a scene, the

the commercial possibilities of desktop VR applications.

**3.3 Semi-immersive virtual environments** 

observer must see slightly different images of the scene under regard in each eye. In the real world this occurs because the two eyes are placed slightly apart in the head, and so each eye views the scene from a slightly different position. Multi-user issues have been reported as one of the main advantages of these systems and designers must consider the handover of control between users as this technology develops.

Virtual environments applications continue to grow. Developers are coming out with new technologies that can simulate effects such as wind, vibration and lightning to enrich the virtual environment for a true model of reality. Virtual environments are being successfully used for applications such as driving and flight simulators and we are now witnessing some entertainment environment like the simulated Viruga Mountains in Rwanda to explore a tribe of Mountain Gorillas.
