Virtual reality (VR) and augmented reality (AR) are booming new technologies transforming how we work, play, and shop. But with the popularity, many new words, terms and acronyms fly around, making it hard to keep up. In this article, we’ll define VR and AR terms and acronyms used within the industry, helping you understand the basics and how to navigate this new reality.
Additionally, this article will be updated when new terms are introduced and popularized.
Here are all the terms:
Virtual reality (VR)
Augmented reality (AR)
Assisted reality (aR)
Mixed reality (MR)
Extended reality (XR)
Head Mounted Display (HMD)
Computer-generated VR (CG VR)
Degrees of Freedom (DoF)
Inertial Measurement Unit (IMU)
Inside-out and Outside-in
Standalone and tethered
Eye and hand tracking
Screen door effect
Field of View (FoV)
Interpupillary distance (IPD)
Liquid Crystal Display (LCD)
Light Emitting Diode (LED)
Mini- and microLED
OLED (Organic Light-Emitting Diodes)
AMOLED (Active-Matrix Organic Light-Emitting Diodes)
The differences between the reality abbreviations are explained by how each achieves immersion.
Virtual reality (VR) is content contained within the view of the wearer. Crudely it is like having an interactive movie theater strapped in front of your eyes.
Augmented reality (AR) is computer-generated content layered on the real world, interacting with it in real-time. It is like having a screen within your sunglasses but with digital 3D objects on your physical table; think PokémonGO.
Assisted reality (aR) is the same as AR but without interactivity with the real world. It is like a static screen plastered on your sunglasses that can show you movies or phone notifications.
Assisted reality is further categorized into two types where the digital information is displayed: monocular and binocular.
Monocular is when aR only is shown in front of one eye. This can be either through an add-on or a visor on one’s head. For example, RealWear HMT-1 is a monocular aR smart glass.
Similarly, binocular means that aR is displayed in front of both eyes, sort of like normal glasses. For example, the upcoming Vuzix Shield will be a binocular aR smart glass.
Mixed reality (MR) is when AR is taken up a notch. MR merges the digital with the real. It is no longer enough to have a digital 3D lamp on your table; with MR you can turn the lamp on, illuminating your room, or change the design and color of the lamp.
Extended reality (XR) is the umbrella term for all the reality-terms both now and in the future. It is for covering all in a neat single term or when enterprises combine one or more realities into unique solutions: like Phario with Varjo headsets.
The metaverse is also known as the embodied internet and is different from Web3.0. The metaverse is the blending of digital and online elements into our real world. In a way, the metaverse is virtual shared spaces that you enter using either virtual or augmented reality. Matthew Ball, a metaverse expert, describes the metaverse as “a massively scaled and interoperable network of real-time rendered 3D virtual worlds which can be experienced synchronously and persistently by an effectively unlimited number of users with an individual sense of presence and with continuity of data, such as identity, history, entitlements, objects, communications, and payments.”
Simply, a virtual reality headset and the term HMD, or head-mounted display are the same. The term itself comes from how it worked in the past when VR was just strapping a contained display in front of your eyes.
Location-based virtual reality is used when VR HMDs (what you just learned) are taken to different locations to be used. An example is when enterprises take VR headsets to their conference stands for presentations.
Stationary VR is a virtual reality station set up to be used within. This category mirrors how the tracking works: see outside-in tracking below. Generally, stationary VR is used by consumers when gaming in their living room or by enterprises developing and designing within a designated VR workstation.
Cinematic VR is also known as 360-degree video and refers to 360-degree video cameras like GoPro MAX. Cinematic VR is video content similar to a movie but experienced as virtual reality.
CG VR is virtual reality content and experiences created on a computer and rendered as 3D objects: think of video games.
Degrees of Freedom refers to how mobile you can be when experiencing virtual reality and if your movements are tracked and simulated in your experience.
3 DoF are the rotational axes that are tracked, namely your head movements of head pivots from side to side, horizontal swiveling (shaking your head signing “no”), and pitching your head up and down (signing “yes”).
In other words, 3 DoF means you must be stationary in one place while only your head movements are tracked.
6 Degrees of Freedom adds three more axes for your movements to be tracked and simulated within the virtual world. These are strafing, moving in a straight line left or right; surging, moving in a straight line front or back; and elevating, moving up or down.
In other words, 6 DoF means you have the freedom to move around.
Similar to how a bat’s echolocation works, LiDAR is a tracking method of shooting a laser onto an object to measure the time it takes for the laser to bounce back. LiDAR is a more effective tracking solution as it can quickly create an intricate and detailed 3D map of the wearer’s surroundings. It even works in complete darkness.
Similar to infrared (IR) tracking, measuring the infrared spectrum or heat signatures.
An IMU or Inertial Measurement Unit is a device that measures, tracks, and reports a headset’s position, angle, and movement from gyroscopes and accelerometers. In other words, an IMU in a headset can track in full 360 degrees your head movements.
What inside-out and outside-in signifies is where the tracking comes from and how free you are when wearing a VR headset.
Inside-out tracking means that the tracking originates from the headset. Naturally, this means that you can be in any environment, and the tracking will still function.
Oppositely, outside-in tracking means that external tracking stations (or bases) are placed around a designated tracking area, i.e., tracking only works within this zone.
If your hands or controller moves outside the embedded tracking camera’s view or the tracking station’s cone, the tracking can stop or stutter. When this happens, these tracking zones are called “dead zones”, as little to no tracking is present.
A guardian in virtual reality is the border of your tracking zone. The guardian appears when you get close to the border, preventing you from stepping past it and possibly into a wall or piece of furniture.
A standalone VR HMD refers to its computing within the headset itself. Again, this means more freedom to experience virtual reality wherever you are.
Oppositely, a tethered VR headset means that the HMD only works if connected to a computer or gaming console. This limits freedom but usually comes with better processing.
Eye tracking is when embedded cameras are placed inside the VR headset to track the pupils of your eyes, keeping track of where you are looking. Recently we have seen more enterprises realize the valuable use cases of eye tracking.
Similarly, hand tracking is when a headset, either inside-out or outside-in tracks your hands’ position, depth, pace, and orientation. Generally, hand tracking increases the immersion of the virtual reality experience.
System-on-Chip or SoC is when all (or most) processing elements are integrated into one closed system. This is compared to traditional motherboard infrastructures where components such as CPU and GPU are kept separate. As a result, SoCs are faster, more power efficient, and enable the possibility for headset manufacturers to produce their own optimized processing. Examples of SoCs are Apple’s M2 and Google’s Tensor.
Foveated rendering is when a headset adapts the screen resolution based on where the wearer is looking through eye tracking. In other words, the headset to conserve processing will blur the edges of your vision without you noticing.
Developed by Magic Leap and featured on Magic Leap 2, dynamic dimming is a lens technology that controls how much real-world light enters the wearer’s eyes. It is so effective that dynamic dimming can block 99.7% of light, making smaller 3D objects more visually distinct. For example, reading text in AR with dynamic dimming is much easier.
Within augmented and assisted reality, a visual effect is known as ‘Ghosting’ and refers to when real-world objects behind 3D objects are visible. If this is very prevalent, it can detract from the immersion of AR/aR and lessen the overall augmented or assisted reality experience. As a note, Dynamic Dimming technology is known to remove ‘ghosting’.
In virtual reality, the screen door effect is when you can see the borders between pixels within the headset, looking like a net or grid is layered over the display. Interestingly, because each person’s eyes are unique, some can see the screen door effect while others can’t. The effect happens because the Pixels Per Inch (PPI) density is low, making you see the individual pixels. The solution, therefore, is to increase the resolution of the virtual reality headset.
FoV, or field of view, refers to how wide the screen is within the virtual reality headset. This can be measured in horizontal and vertical degrees or combined into diagonal degrees. Similarly, there are differences between the visible FoV and the rendered FoV: the visible is what you can see, and the rendered is the totality of the screen, including parts that cover the screen.
The distance between your two pupils is called interpupillary distance, or IPD. Virtual reality uses this distance – measured in millimeters – to customize the different IPD distances of people to improve the visual experience. Think of when you dial in the width on binoculars before you can see anything; VR works the same way.
Some virtual reality HMDs feature either one or more cameras on the front of the headset’s visor. These cameras are usually used as tracking sensors but can also be activated to show on the internal VR screen, enabling you to see the outside world from inside the headset. That is video passthrough.
The simplest difference between each display type is the source of its backlighting. Essentially, a display works by having a coating of pixels that are alit by a light source.
LCDs produce an image by obscuring the light produced from behind them. In other words, based on this obfuscation of the backlight, an image is made. LCD engines are the more cost-effective and thereby popular displays to use in virtual reality.
An LED display is an LCD with the backlight coming from a panel of light-emitting diodes (LEDs). In other words, it is just an LCD with unique backlighting.
MiniLED is the same as microLED. The only difference is that Samsung pioneered and pushed the microLED term.
MicroLED is when you combine the pixels into their own light source: the light emitting diodes. It is minuscule LEDs acting as display and light source slimming the display and weight.
OLED displays are light-emitting diodes but organic, meaning dynamic. Effectively, each organic diode is its own pixel and light source, slimming the display thickness and weight.
The display type that premium virtual reality headsets use is active-matrix organic light-emitting diodes or AMOLED displays. The reason is that AMOLED compresses more display parts (or layers) tighter together. This means AMOLED can change and turn on and off faster than OLED displays creating a smoother visual experience.
Most experts believe the human eye can perceive images between 30 to 60 frames per second, whereas some posit we can notice flickering up to 90 frames per second. This is important because VR encapsulates a screen closely in front of a wearer’s eyes, so a smooth visual experience is pivotal. In virtual reality, the higher the refresh rate, the better, alleviating motion sickness and increasing immersion.
Also, OLED and AMOLED displays produce the highest refresh rates, as the light source and pixel are together in one element.
The fresnel lens technology is the oldest and most widely used within virtual reality. Fresnel works like a lighthouse in that concentric lens circles beam and enhance a screen’s light into the wearer’s eyes.
The pancake design works by bouncing and redirecting the screen’s light between multiple lenses layered like a stack of pancakes. This slims the VR headset enabling more stylish designs.
Aspherical lenses work the same as cameras. The aspherical lens achieves the same enhancement and beam effect as the fresnel but does it through a smooth dome. This means that light distortions such as God Ray’s (visible light beams) are avoided, and a better visual experience is delivered. Virtual reality headsets using the aspherical lens are Varjo VR-3 and Varjo Aero.
Waveguide optics is a type of lens used within augmented and assisted reality. It has enjoyed recent economies of scale, bringing down manufacturing costs, increasing the number of AR/aR headsets with waveguides. The optics technology improves visual clarity and minimizes double-images, while it enables a thinner and lightweight form factor.
Jakob Pii is Writer at VR Expert and currently lives in the UK. He started his career in VR gaming in 2015 and has stayed in XR since, from exposure therapy in VR to 360-degree video documentaries. He is fascinated by how emerging technologies change how we live, play and work.