VIRTUAL REALITY

 

VIRTUAL REALITY

1. Introduction

The constant development of computer and information technology allows the implementation and application of new methods and systems that were previously not possible. One example of such a development is the technology of virtual reality (VR) or virtual environment (VE). With virtual reality techniques, it is possible to achieve realistic simulations that are useful in many areas of human activity. Simulations were known even before, but virtual reality techniques can provide the impression of “stepping in” the apparent world

his impression of presence in the apparent world is possible by using advanced computer and communication devices between a man and a computer. Virtual reality techniques also use modern computer networks to achieve communication between a man and a remote environment with the aim of achieving functioning at a distance.

At the beginning of the twentieth century, public perception of virtual reality was quite distorted. In fact, thanks to its presence in the media, virtual reality was expected to be a miracle. But, despite some predictions, virtual reality did not come into extensive use. Thus, a part of the public and some experts changed their minds significantly and declared that technology is useless

 

2. Definition and principles of virtual reality

To make the concept and principle of virtual reality clear, at the very beginning it is necessary to clarify the concept of perception. Perception is the process in which man collects and interprets information about the world around oneself. Senses and the brain participate in the process of perception.

There are two kinds of senses—external and internal. External detect phenomena outside the body, and the inner detect the phenomena within the organism (hunger, fatigue, pain, thirst, etc.). The external senses can be divided into remote (heat, eyesight, hearing) and contact (smell, touch, taste). When it comes to virtual reality, only systems that affect the remote senses are well developed, though systems that affect the contact senses will gradually evolve in the future.

Senses transfer information from the environment, while the brain interprets received information. Beside the senses, the perception is also influenced by experience, knowledge, emotion, and motivation. In order “to cheat” the system of perception, the basic idea is that the real stimuli received by the senses should be replaced by artificially generated stimuli. In this way, the real environment can be replaced by apparent environment. As a result, it appears that the system of perception creates the impression of the presence of people in the apparent, nonexistent environment.

Virtual reality is a computer-created sensory experience that allows the user to believe in the apparent reality. The user is then either completely surrounded by this virtual world or partially included by listening and watching virtual reality applications. Virtual reality is a collection of technologies that “inserts” users in a virtual environment. Ideally the user’s senses detect only virtual stimuli produced by a computer, and user’s movements are directly entered in the computer.

Virtual environments are based on objects defined in the computer’s memory in such a way that a computer can later be attached to these items on the screen with the possibility of interaction. By combining the elements of the unreal (imaginary) environment and the real environment (which can also be remoted), the user creates a feeling of presence in a virtual environment.

 

The following figure shows the basic principle of virtual reality. The user is in a closed loop and one is connected to a computer with input and output units. Input devices (1) follow the movements of the user and pass them to the computer (2), which makes the simulation of a VE to be based on these and other data. With the help of output units (3) the computer shows a virtual environment, as real as it is possible. Ideally, the user’s senses should only detect artificially generated stimuli (from the computer), and thus the real would be completely turned off. In the example shown in Figure 1, the user (4) sees only the image generated by the computer. Thereby, the loop is closed, and the user directly sees and hears (and possibly feels, smells, tastes, etc.) virtual environment with the immediate results of his own movements.

3. Virtual reality equipment

Firstly, virtual reality devices can be divided into input and output. Secondly, previously mentioned devices can be further divided into types and subtypes within each category. The input devices include the following:

1.   Position/orientation sensors—electromagnetic, acoustic, optical, mechanical, and inertial

2.   Force/momentum sensors—Spaceball, etc.

3.   Body/arm position sensors—sensor glove (data glove) and sensor suit (bodysuit)

4.   Motion sensors—treadmill, bike ergometer, rowing ergometer, etc.

5.   Other sensors—control through breathing, face tracking, eye tracking, and voice recognition

6.   Electromagnetic sensors

7.   Acoustic sensors

8.   Optical sensors

9.   Mechanical sensors

10.Inertial sensors

11.Force sensors

12.Body position sensors

13.Arms position sensors

 

The output devices include:

·         Devices for 3D display—stereo glasses, head-mounted display, stereo screens (with interchanging images or double vision), and projection systems (stereo projection on a screen, cave automatic virtual environment (CAVE), wide-angle projection, virtual worktable)

·         Devices for 3D sound synthesis

·         Devices for synthesis of sense of touch and force—tactile output devices, devices for force feedback, and the mobile platform

·         Other devices—odor, wind, and heat

 

In order to achieve the stereoscopic effect, it is necessary to project two images, one to each eye at a time. Head-mounted display (HMD) has a separate screen for each eye. Due to the small dimensions of the device, the screens are too close to be directly observed, so it is necessary to set the corresponding optical system that allows the user to view the screen, between the eye and the screen itself.

 

 

The most important characteristics of HMD, apart from the size, weight, and comfort, reflect in the range of view angle and screen resolution. They can be found in various forms, from the helmet to the goggles. Today, there is a tendency toward minimalist approach and practical applicability. The aim is to create a device that is small enough not to interfere free movements. Such devices can be equipped with headphones and position and orientation sensors.

The most advanced projection system is CAVE system. It consists of the area bounded by the projection screen (which creates the room where the user is located) on which are projected computer-generated stereo images. The user wears glasses which guarantee a three-dimensional experience, thus providing the satisfactory peripheral vision. The experience is very realistic so that connections between the set of projection canvases is almost invisible.

Sound simulation includes the reproduction or generation of a sound in a virtual environment. By including a three-dimensional sound, we can get an idea of precise location of the sound source in space. The effect can be achieved by the difference in received sound volume in the left and the right ear, by the reflection of sound waves in the ear lobe and its surrounding, and by combining the results of this reflection for different frequencies, which are an integral part of the sound.

Haptic devices allow the simulation of touch and/or force that can cause the sensation of contact (touch) with the virtual object. Simulation of touch (tactile feedback) is usually based on thermal or vibrating elements which the user wears on his fingers and that are activated when the user “touches a virtual object.” For this operation, one has to track accurately the location of user, more precisely his hands. Simulation of force (force feedback) includes the monitoring of the position with the inclusion of active elements (motors, electromagnets, servo motors) that exert force on a user’s hand, other parts of the body, or a tool one handles.

Moving platforms are haptic systems that simulate the position of the user by moving the entire platform on which the user stands or sits. Compliance of the position with the visual information increases the feeling of participation in the simulation. This type of haptic systems is commonly used in complex simulators, car or plane driving simulators, etc.

 

 

4. Applications of virtual reality

Virtual reality is mostly applied in the following areas: medicine, military industry, education, entertainment, design, and marketing.

Medicine is the field where the virtual reality had an enormous success and it is still expanding. It is used in the field of surgery, both for training (learning on virtual human models) and for planning of a surgery. 3D displays can be obtained from medical images, as it is the case in modern medical devices. In psychiatry, the virtual reality is used to treat a variety of mental disorders, starting from fear of flying to posttraumatic stress disorder

One of the biggest investors in the field of virtual reality is military organization, and many VR technologies are embedded in various military equipment simulators. Simulations of various vehicles are among the most common applications of virtual reality. Many experts are trained in different simulators, and it is particularly important that the situations which in reality rarely occur (e.g., rescue of hostages) can be trained.

Virtual reality can also be used for the presentation of future projects in architecture, for creation of future product prototypes, etc. It can be also used as a successful tool for the promotion and marketing at exhibitions and fairs because of the fact that 3D projection is still interesting enough to attract the curious

Virtual reality is ideal for the entertainment industry, because of its possibility to create an illusion. More and more games that use this technique are turning up in gaming lounges, and it is a question of time when this technology will be available to everyone who wants to use it, even at home.

Despite the numerous areas of application, there are also some limitations. Although in recent years, there has been a considerable progress, the equipment is still impractical, huge, expensive, and complex. Certain types of virtual reality can cause nausea, and even if they do not cause certain health issues, they are too uncomfortable for long-term use

 

 

5. Augmented reality

Augmented reality (AR) adds the elements of virtual environment to the real world so they could look like the part of it. This user’s view of the world expands with additional information that are directly embedded into the real world. In some applications, it is not necessary to replace reality with the virtual world, sometimes it is only requisite to complement or enhance it with some parts of virtual reality.

Augmented reality is a relatively new area. Although the basic idea appeared in the beginning of twentieth century, its rapid development has started at the end of the same century. That is the reason why this technology has not still achieved its full expansion. It provides direct access to the information so that they are displayed in the user’s field of vision and intertwined with the real world. This allows faster, better, and easier access to information. It can be applied in the following areas: medicine, manufacturing and maintenance, architecture, robotics, military industry, and entertainment. When it comes to medical application, medical images are overlaid with the patient, resulting in a kind of virtual X-rays but in real time. The resulting effect is reflected in the fact that the doctor can see the patient’s organs as the body is transparent. For now, they are not widely used. In the production and maintenance, visual instructions are displayed directly on the equipment/machinery, and the operator, instead of looking the documentation, has all the necessary information at the right time in the right place. Augmented reality can be used in interior design, visualization of structures, or installations. For example, virtual furniture can be deployed in the actual room; thus, one can get an impression of spatial relations and how the rooms will really look like with some furniture. With the help of augmented reality, military pilots can receive additional information, such as guidance, see the targets or guided missiles. The display is built into the helmet or in the cabin.

 

Augmented reality has a great potential, but today’s systems of augmented reality are still quite cumbersome and imprecise and consume too much energy, so it is necessary to solve these problems.