- Tethered VR headsets (a.k.a. PC VR, desktop VR)
- Standalone VR headsets (a.k.a. all-in-one VR, wireless VR)
- Smartphone VR headsets (a.k.a. mobile VR, VR viewers)
There are specs common to all types of virtual reality headsets, as well as features that are specific to different types of VR headsets. Each type of HMD has its pros and cons!
How to choose a VR headset?
These factors’ order of importance lies in the user’s preference and needs.
External sensors enable room-scale and positional tracking (outside-in).
Positional tracking and room scale
Positional tracking is the precise tracking of the VR headset’s position (and, therefore, the user’s position). The more precise the tracking is, the better the VR immersion. If there is a gap or lag between the user’s position in real-life and in-game, it may greatly hinder the user’s experience. It is possible to have external or internal positional tracking:
- Outside-in tracking: makes use of external sensors and/or cameras to accurately track the headset’s position within a delimited space (room-scaling). For full room scale, users need to install more than two sensors to avoid any occlusion.
- Inside-out tracking: the VR headset uses one or more front-facing cameras to detect its position, with or without the aid of markers. This type of tracking is generally less powerful and accurate than outside-in tracking.
Other kinds of tracking
Apart from positional tracking, there is also:
- Hand tracking: most high-end PC VR headsets enable hand tracking either with advanced controllers or sensor technology (ie. Leap Motion technology). This enables users to precisely and freely interact with their VR experience.
- Eye tracking: a module inside the headset tracks the user’s gaze. Few headsets have this feature, as the technology is still complex.
It’s also possible to track a person’s entire body thanks to special suits, but the development is still ongoing and most products are at a prototype stage.
DoF: Degrees of Freedom
Degrees of Freedom (DoF) is the number of movement types that the user may experience. In VR, headsets offer either 3DoF or 6DoF.
3DoF (360° tracking) provides rotational freedom (users turning their heads). 6DoF (room scale tracking), in addition to rotation, provides positional freedom (up/down, left/right, forward/backward).
6DoF offers a more immersive experience.
FOV: Field of View
The wider the field of view, the better. For reference, the human FOV (with eye rotation) reaches a maximum of 220°. Most VR headsets provide a horizontal FOV of around 100 degrees, but some HMDs like the Pimax 8K may go up to 200°. If the field of view is too small, it will greatly reduce the sense of immersion.
Types of degrees of freedom– 3DoF versus 6DoF.
Credit: (adapted from) @YuukiOgino
Being able to use good controllers can greatly enhance a virtual reality experience, especially when it comes to gaming. Those who are looking into VR games should consider headsets that come with decent controllers. High-end 6DoF controllers can be tracked by the headset and/or its sensors and have a trackpad, trigger, and buttons to allow for more in-game control. For casual gaming and VR viewing, simple 3DoF pointer controllers (point-and-click) should be sufficient. Some headset brands develop their own VR controllers and/or allow users to connect third-party VR controllers.
Just like at the movie theater, audio plays a big role in helping users feel immersed. Entry-level VR headsets generally have built-in speakers, while higher-end VR headsets sometimes provide built-in headphones. Also, VR headsets that feature a built-in microphone allow users to communicate with others in-game or use voice control.
The 3DHead, a large and heavy VR headset from 2015.
Credit: Business Insider
Weight and fit
Since the display lens and computing hardware are positioned in front of the user’s eyes, that’s where most of the weight lies. This may put some pressure on the nose and cheekbones. The result is what is commonly called “VR face“, when users’ faces are left with red marks.
That’s why VR headset manufacturers try their best to balance their designs, in order to put less weight on the person’s face. Even with balance, though, it’s best to choose a lightweight headset. Smartphone VR users must take into account the additional weight of their smartphone once inside the headset.
Another factor that greatly helps is the headset’s adjustability. Most headsets on the market have adjustable head straps or tightening knobs to provide a relaxed fit.
Users that wear eyeglasses should also check if there is enough room for them under the headset. In some cases, users may order their VR headset with specific prescription lenses.
Almost all headsets have special cushions to make the VR HMD more comfortable to wear. The cushion is, obviously, in direct contact with the user’s skin and sweat (the unglamorous side of VR).
Those who have sensitive skin should first check if the material is skin-friendly. It is also beneficial to be able to remove the cushion and clean it from time to time.
There are computing components and processors inside the headset that give off heat as they process games and VR experiences. Users should make sure that there is enough ventilation and/or a cooling system for higher-end VR headsets.
Simulation sickness, or VR sickness
Some users may experience a sort of motion sickness linked to low refresh rates or a specific VR experience. It is the same feeling as transportation sickness– the eyes and brain tell the body they are moving, but the inner ear stands still.
In the industry, it is referred to as simulation sickness, virtual reality sickness or even cybersickness. There are a few tips on how to avoid VR sickness, but low latency and high refresh rates may help prevent it from happening in the first place.
A good starting refresh rate is 60 Hz, although most VR headsets offer rates between 90 and 120 Hz.
Understanding IPD, interpupallary distance. Credit: ARVI Lab
Content platforms and apps (content feeds)
Applications of VR and types of VR content
Gaming and entertainment are the most common application fields for VR, but there are other industries that benefit from this technology:
- Education and training
- Medical and healthcare
- Social sciences and psychology
- Digital marketing and sales
- Engineering and design
Aside from games, there are different types of VR content and experiences available, including:
- Cinematic VR: these VR movies allow the user to feel as if they were the main actor.
- Virtual theater: it’s possible to watch movies as if inside a movie theater, but the movies aren’t in VR.
- Fish tank VR: users may view and explore the virtual reality space, but not interact with it.
- VR ride: these experiences, often roller coaster rides, are videos shot in 360° from a person’s perspective.
- Social VR: users may virtually meet up with others on social platforms, like VRChat.
There are more advanced types of experiences with hyper-reality, where users may actually feel the VR environment and content (touch, smell, etc.). This is only available in dedicated VR parks or spaces such as the VOID.
- Content exclusivity: some games are only available on certain platforms. The choice may be comparable to choosing between different gaming consoles (Xbox One, PlayStation 4, Nintendo Switch, etc.).
- Quantity and update frequency: consider if the platform often has new content? Is content updated regularly to fix bugs?
- Open development vs. closed development: open development platforms allow any developer to create and upload their own applications. They don’t necessarily impose quality standards or criteria, contrarily to closed development platforms that ensure the content is worthy enough before making it available.
Tethered VR headsets (desktop VR, PC VR): technical considerations
PC requirements (minimum specs)
As mentioned earlier on, tethered VR almost always requires a powerful PC. It’s important to look at the minimum PC requirements before acquiring a desktop VR headset. Minimum requirements mainly concern:
- GPU (Graphics Processing Unit)
- CPU (Central Processing Unit)
- RAM (Random Access Memory)
Some PC VR headset manufacturers provide a list of compatible PCs or an online compatibility tool. Users that do not yet own a powerful PC should ensure that their next PC is “future-proof”, as VR headsets require powerful and modern components.
Tethered VR headset cable management system.
Cable number and length
A tethered connection is PC VR’s main characteristic, and raises a few questions:
- Is there a high number of cables that may make the headset difficult to install or use?
- Is the cable long enough for users to walk around comfortably?
In some cases, users will find it necessary to have a special cable organizer and holder. Indeed, the cables must not impede the user’s movements, and must be suspended from the ceiling.
External sensors enable tracking the VR headset’s position within a delimited space.
- Does the headset require any external sensors or does it have inside-out positional tracking?
- If the headset does require external cameras or sensors (a.k.a base stations or lighthouses), are they easy to install?
Users will also need to see if they have enough space to be able to install external sensors and have room to play.
VR headset lenses
Since the headset’s display is very close to the user’s eyes, special lenses are needed to bend the image and light. This makes it easier on the eyes, by making it seem as if the objects were farther away.
Fresnel lenses and their hybrids are the most common type of lenses for virtual reality as they are thinner and lighter than normal lenses. However, researchers are developing higher-quality lenses that are even more lightweight and flat.
The display– single or dual– is what users’ eyes will most be focusing on for hours. Therefore, along with a wide FOV, displays should be of good quality and with a high resolution.
As it is the case with televisions or smartphones, a higher resolution is best. One of the best resolutions available in 2018 is 4K.
There are other, more complex display specifications that users can evaluate, such as pixel density, color fidelity, dynamic range, and brightness. Medium’s Michael Naimark explains this into more detail.
Standalone VR headsets: technical considerations
Just like for any battery-powered device, it’s important to know how long it’s possible to use the headset before it needs to charge again. Users may also want to know how long it takes to charge the battery.
For example: if the battery lasts one hour but needs eight hours to charge, many users will find that this isn’t very efficient.
Manufacturers don’t always provide this information, but it may be available in community reviews.
Expectations for standalone VR headset displays are much lower than with desktop VR. All-in-one virtual reality headsets are less powerful and can’t support the same quality displays as PC VR.
Most wireless VR headsets have a decent resolution of 2560 x 1440 pixels.
Standalone VR headsets provide internal storage for users to save content. The Oculus Go, for example, is available in 32Gb and 64Gb versions. Some VR headsets feature an SD card (or mini SD) slot for even greater storage.
Smartphone VR headsets: technical considerations
The two main limitations for smartphone VR are:
- Screen size: most smartphone VR headsets are compatible with smartphone screen sizes between 4.5 inches and 6 inches. Some are made especially for tablets.
- Operating system (OS): varies between Android, iOS, and both.
Does the headset sufficiently hold the smartphone? Will it fly out if the user makes sharp movements?
The Google Daydream View 2, a smartphone VR headset.
Smartphones have a tendency to heat up during long periods of use, especially when users watch videos or play games. It’s therefore important for there to be enough cooling space within the VR headset or air vents in order to avoid overheating.
It’s important to consider that VR puts heavy strain on batteries, like many mobiles games and apps do. Users may need to recharge their phones after a couple hours of use depending on the smartphone’s capacity.
What will VR be like in the future?
It is becoming possible for certain VR headsets such as the VIVE Pro to integrate augmented reality (AR), providing true mixed reality (MR).
Also, more content– both quality and quantity– is inevitable and necessary to the survival of virtual reality. This content will stretch out from casual games, movies, and rides to reach educational, professional, and industrial users.
Another side to VR that is evolving as well is accessories such as treadmills and haptic gloves or full bodysuits like in the Ready Player One movie. However, it may take a while before these high-tech accessories become widely available.
Disclaimer: although we strive to provide fresh content, information and technology in the virtual reality sector is in constant evolution. We recommend doing complementary research before taking any decisions.