Virtual reality literally makes it possible to experience anything, anywhere, anytime. It is the most immersive type of reality technology and can convince the human brain that it is somewhere it is really not. Head mounted displays are used with headphones and hand controllers to provide a fully immersive experience. With the largest technology companies on planet earth (Facebook, Google, and Microsoft) currently investing billions of dollars into virtual reality companies and startups, the future of virtual reality is set to be a pillar of our everyday lives.
A realistic three-dimensional image or artificial environment that is created with a mixture of interactive hardware and software, and presented to the user in such a way that the any doubts are suspended and it is accepted as a real environment in which it is interacted with in a seemingly real or physical way.
Virtual reality (also called Virtual Realities or VR) is best understood by first defining what it aims to achieve - total immersion. Total immersion means that the sensory experience feels so real, that we forget it is a virtual-artificial environment and begin to interact with it as we would naturally in the real world. In a virtual reality environment, a completely synthetic world may or may not mimic the properties of a real-world environment. This means that the virtual reality environment may simulate an everyday setting (e.g. walking around the streets of London), or may exceed the bounds of physical reality by creating a world in which the physical laws governing gravity, time and material properties no longer hold (e.g. shooting space aliens on a foreign gravityless planet).
Several categories of virtual reality technologies exist, with more likely to emerge as this technology progresses. The various types of virtual reality differ in their levels of immersion and applicational use cases. Below, we explore a few of the virtual reality categories:
Non-immersive simulations are the least immersive implementation of virtual reality technology. In a non-immersive simulation, only a subset of the user's senses are stimulated, allowing for peripheral awareness of the reality outside the virtual reality simulation. Users enter into these three-dimensional virtual environments through a portal or window by utilising standard high resolution monitors powered by processing power typically found on conventional desktop workstations.
Semi-immersive simulations provide a more immersive experience, in which the user is partly but not fully immersed in a virtual environment. Semi-immersive simulations closely resemble and utilize many of the same technologies found in flight simulation. Semi-immersive simulations are powered by high performance graphical computing systems, which are often then coupled with large screen projector systems or multiple television projection systems to properly stimulate the user's visuals.
Fully-immersive simulations provide the most immersive implementation of virtual reality technology. In a fully-immersive simulation, hardware such as head-mounted displays and motion detecting devices are used to stimulate all of a user's senses. Fully immersive simulations are able to provide very realistic user experiences by delivering a wide field of view, high resolutions, increased update rates (also called refresh rate), and high levels of contrast into a user's head-mounted display (HMD).
In order for the human brain to accept an artificial, virtual environment as real, it has to not only look real, but also feel real. Looking real can be achieved by wearing a head-mounted display (HMD) that displays a recreated life size, 3D virtual environment without the boundaries usually seen on TV or a computer screen. Feeling real can be achieved through handheld input devices such as motion trackers that base interactivity on the user’s movements. By stimulating many of the same senses one would use to navigate in the real world, virtual reality environments are feeling increasingly more like the natural world. Below, we explore some of the key components to behind this system.
Inside of each virtual reality head-mounted display (HMD) is a series of sensors, individual eye displays, lenses, and display screen(s), among other various components. The Ifixit Oculus Rift teardown offers an excellent step-by-step teardown and look inside of one of the most popular virtual reality headsets. Below we explore some of the key components inside of a virtual reality headset.
The three most common sensors in a virtual reality headset are magnetometers, accelerometers and gyroscopes. These sensors work together by measuring the user’s motions and direction in space. Their ultimate goal is to achieve true six-degrees-of-freedom (6DoF), which covers all the degrees of motion for an object in space.
Lenses lie between your eyes and pixels on the display screen(s). They focus and reshape the picture for each eye by angling two 2D images to mimic how each of our eyes take in views of the world (also called stereoscopic). This creates an impression of depth and solidity, which we perceive to be a three-dimensional image. Lenses on each virtual reality device are not one-size-fits all and have to be adjusted for initial use as all devices have different lens properties.
Display screens show the images that user view through the lenses. They are typically LCD and receive video feed from the computer or smartphone. Depending on the headset, the video feed is either sent to one display or two displays (one per eye). This happens via wireless connection, smartphone connection, or HDMI. The most common types of virtual reality display technology is a Liquid Crystal Display (LCD) screen, similar to the kinds used in smartphones and computer monitors. An alternative display technology is an Organic Light-Emitting Diode (OLED) screen.
Virtual reality systems demand a substantial amount of power, even in comparison to notoriously power hungry gaming systems. The processing power required by virtual reality systems can be broken down into several categories:
Field of view (also called Field of Vision or FOV) is an important component used in virtual reality to provide users with a realistic perception of their environmental landscape. Simply put, field of view refers to how wide the picture is. Field of view is measured based on the degree of display (e.g. 360°). Most high-end headsets make do with 100° or 110° field of view which is sufficient for most virtual reality content.
Frame rate refers to the frequency (rate) at which the display screen shows consecutive images, which are also called frames. Television shows run at 30 frames per second (fps) and some game consoles run at 60 frames per second (fps). In virtual reality, a minimum frame rate of approximately 60 frames per second is needed to avoid content stuttering or cause of simulation sickness. The Oculus Rift runs at 90 fps, providing Oculus Rift users with a very lifelike experience. Future Frame rates for virtual reality headsets are set to inevitably continue getting faster, providing for a more realistic experience.
Latency refers to the amount of time it takes for an image displayed in a user’s headset to catch up to their changing head position. Latency can also the thought of as a delay, and is measured in milliseconds (ms). In order for an experience to feel real, latency usually needs to be in the range of 20 milliseconds (ms) or less. Low latency, or very little delay, is needed to make the human brain accept the virtual environment as real. The lower the latency, the better. The higher the latency, a noticeable and unnatural lag may set in, consequently causing simulation sickness for the user.
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.
Tracking handles the vital task of understanding a user’s movements and then acting upon them accordingly to maintain full immersion in virtual reality. Below, we explore the three of the main types of virtual reality tracking:
A well established example of virtual reality already in use is in the field of aviation training. From flying a commercial airplane out of a crowded international airport, to training for a dangerous night-flight using only night vision, virtual reality can provide significant benefits to aspiring pilots.