Virtual Reality is a major asset and aspect of our future. It is the key to experiencing, feeling and touching the past, present and the future. It is the medium of creating our own world, our own customized reality. Modeling is used to build structures that serve as proxies for other objects. Virtual reality is more than just interacting with 3D worlds. By offering presence simulation to users as an interface metaphor, it allows operators to perform tasks on remote real worlds, computer generated worlds or any combination of both. The simulated world does not necessarily have to obey natural laws of behavior. Such a statement makes nearly every area of human activity a candidate for a virtual reality application. However, we can identify some application areas were benefits are more straightforward than others.
Overview of Virtual Reality
A virtual reality system is essentially an interactive simulation that can represent a real or abstract system. Virtual Reality (VR) is the use of computer graphics and other technologies to create a simulated environment in which the user interacts. While computer graphics supplies the visual component of the experience via a normal screen, a stereoscopic display, or head‐mounted technology; a variety of other devices can be used to allow the user to experience the interaction. For example, a head tracking device can allow the scene to change when the user moves their head, a force feedback joystick can be used when a pilot is flying a VR simulator, or data gloves can be worn to touch and move objects in the virtual world The key is that the user has a sense of being immersed in a virtual world in which they are engaged.
Virtual Reality (VR) is the use of computer technology to create a simulated environment. The simulation is a representative computer based model, which provides appropriate data for visualization or representation of the system. Unlike traditional user interfaces, VR places the user inside an experience. Instead of viewing a screen in front of them, users are immersed and able to interact with 3D worlds. By simulating as many senses as possible, such as vision, hearing, touch, even smell, the computer is transformed into a gatekeeper to this artificial world. The only limits to near-real VR experiences are the availability of content and cheap computing power.
General Representation of Virtual Reality System
Virtual reality (VR) creates a virtual environment to visualize the real world medium. This technology allows user to have perception of presence by immersion and intuitive interaction through the computer interface. Block diagram of a simple virtual reality system is illustrated in Figure 1. The figure consists of capturing, pre-processing, encoding, transmission, decoding and displaying the video sequences.
Figure 1: Block diagram of Virtual Reality
Capturing: the VR video capturing process includes multi-camera setup in order to record the whole 360 degree scene in raw format
Pre-processing: the captured video content is pre-processed in this step prior to encoding operation. The process may include filtering, color correction, stitching, format conversion, etc.
Encoding: compression operation on the pre-processed video is applied in this step for efficient storing or streaming purposes. The state of the art compression standards used in this process e.g. H.264/AVC and H.265/HEVC.
Transmission: the compressed data is transmitted to the end user through the network to be consumed in the VR devices.
Decoding: the end user receives the bit stream through the network on his/her device (e.g. mobile phone) and the transmitted video is decoded using the implemented decoder in the device.
Rendering/display: the decoded video content is rendered in this step and displayed in the head mounted displays. The rendering and displaying process may include some post-processing operations prior to displaying e.g. post-filtering, stitching, re-sampling, etc.
Virtual Reality technology
Virtual Reality’s most immediately-recognizable component is the head-mounted display (HMD). Human beings are visual creatures, and display technology is often the single biggest difference between immersive Virtual Reality systems and traditional user interfaces..
With a multiplicity of emerging hardware and software options, the future of wearables is unfolding but yet unknown. Concepts such Google Cardboard, Samsung GearVR and Epson Movario are leading the way but there are also players like Meta, Avegant Glyph, Daqri and Magic Leap who may surprise the industry with new levels of immersion and usability. Whomever comes out ahead, the simplicity of buying a helmet-sized device that can work in a living-room, office, or factory floor has made HMDs center stage when it comes to Virtual Reality technologies.
 “Virtual Reality”, spring 2010, available online at: http://dinoonline.net/Readings/Virtual%20Reality.pdf
 Gobbetti, Enrico, and Riccardo Scateni. “Virtual reality: Past, present, and future.” Virtual environments in clinical psychology and neuroscience: Methods and techniques in advanced patient-therapist interaction (1998).
 Ramin Ghaznavi Youvalari, “360-Degree Panoramic Video Coding” Master of Science Thesis, (2016).
 Pallavi Halarnkar, Sahil Shah, Harsh Shah, Hardik Shah and Anuj Shah “A Review on Virtual Reality”, IJCSI International Journal of Computer Science Issues, Vol. 9, Issue 6, No 1, November 2012
 Brian Jackson, PhD on June 3, 2015, “What is Virtual Reality? [Definition and Examples]”, available online at: https://www.marxentlabs.com/what-is-virtual-reality/