This section shows an overview of VR systems from hardware to software to human perception to understand the working of entire VR systems.

The hardware produces stimuli that override the senses of the user [22] based on human motions. The VR hardware accomplishes this by using sensors for tracking motions of user such as button presses, controller movements, eye and other body part movements. It also considers the physical surrounding world because only engineered hardware and software does not constitute the complete VR system. The organism (users) and its interaction with the hardware is equally important.

VR hardware constitute of sensors which act as transducer to convert the energy it receives into a signal from an electrical circuit. This sensor has receptor to collect the energy for conversion and organism has sense organs such as eyes and ears for the same purpose. As the user moves through the physical world, it has its own configuration space which are transformed or configured correspondingly.

VR devices are the hardware products used for VR technology to happen. The different key components of VR system are discussed below. The figure (number) shows the high-level view of Virtual World Generator (VWG). The inputs are received from the user and his surroundings and appropriate view of the world are rendered to displays for VR experiences.

Personal Computer (PC)/Console/Smartphone

Computers are used to process inputs and outputs sequentially. To power the content creation and production significant computing power is required, thereby making PC/consoles/smartphones important part of VR systems. The VR content is what users view inside and perceive so it is equally important as other hardwares.

Input devices

Input devices provides users the sense of immersion and determines the way a user communicates with the computer. It helps users to navigate and interact within a VR environment to make it intuitive and natural as possible. Unfortunately, the current state of technology is not advanced enough to support this yet. Most commonly used input devices are joysticks, force Balls/Tracking balls, controller wands, data gloves, trackpads, On-device control buttons, motion trackers, bodysuits, treadmills and motion platforms (virtual omni).

Output Devices

Devices that each stimulate a sense organ. Output devices are used for presenting the VR content or environment to the users and it is utmost devices to generate an immersive feeling. These include visual, auditory or haptic displays. Like input devices, the output devices are also underdeveloped currently because the current state-of-art VR system does not allow to stimulate human senses perfect ideal manners. Most systems support visual feedback, and only some of them are enhanced it by audio or haptic information.

Apart from input, output hardware and its coordination, the underlying software is also equally important . It is responsible for the managing of I/O devices, analyzing incoming data and generating proper feedback . The whole application is time-critical and software must manage it: input data must be handled timely and the system response that is sent to the output displays must be prompt in order not to destroy the feeling of immersion. The developer can start with basic software development kit (SDK) from a VR headset vendor and build their own VWG from scratch. SDK usually provide the basic drivers, an interface to access tracking data and call graphical rendering libraries. There are some ready-made VWG for particular VR experiences and has options to add high-level scripts.

Virtual reality audio may not be as technically-complex as the visual components, however, it is an equally important component to stimulate a user’s senses and achieve immersion. Most virtual reality headsets provide users with the option to use their own headphones in conjunction with a headset. Other headsets may include their own integrated headphones. Virtual reality audio works via positional, multi-speaker audio (often called Positional Audio) that gives the illusion of a 3-dimensional world. Positional audio is a way of seeing with your ears and is used in virtual reality because it can provide cues to gain a user’s attention, or give them information that may not be presented visually. This technology is already quite common and often found in home theater surround sound systems.

Understanding a physiology of the human body and the optical illusions are important to achieve maximum human perceptual without side effects. The human senses using different stimulus, receptor and sense organ.
As virtual reality are supposed to simulate the real world, it is important to know how to “fool the user’s senses” to know what are the most important stimuli and what is the accepted quality for subjective viewing? Human vision provides the most of information that are passed to our brain followed by hearing, touch and other senses. System synchronization of all stimuli with user’s actions are also responsible for proper functioning of VR system.