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VR Terms You Need to Know

VR Terms You Need to Know

ALL IN ONE

“All in one” or standalone headsets incorporate the main processor, GPU, and tracking cameras into the headset. No external computers or cables are required. Most of these headsets run a system on a chip from Qualcomm called the XR2. The new Pico 4 and Meta Quest Pro run the XR2+ which has more onboard memory. Apple will release a headset soon that runs some version of their new A or M class chips.

Developers are learning to get more and more out of these chips. While it will be a while before they compete with gaming consoles for graphic quality, the immersion, cost, and convenience more than make up for it.

FIELD OF VIEW (FOV)

FOV is the amount of the virtual environment a user can see while wearing a device. In VR, the FOV is typically stated as horizontal because that’s the primary limitation of the technology right now.

FOV Degree

A human FOV is about 220°. The best headsets for LBVR are the Focus 3 and VIVE Pro 2 at 120°, both from HTC.

The Pico Neo 3 and the HP Reverb G2 only offer 98° (not to be confused with the boy band).

The upcoming Pico 4 ups the FOV to 105° and the newly released Meta Quest Pro is 106°. Both of these headsets use what’s called Pancake Optics (see description below), which trades off FOV for weight and volume. If that trade-off is worth it is a matter of opinion.

For gaming, FOV is important. Your peripheral view lets you see and react to things in your environment. This increases immersion and depth of gameplay. Weight and volume are important too, especially as younger audiences embrace virtual reality. But for LBE, with most games being short, I would probably choose a wider FOV over pancake lenses for now. Within two years, you won’t need to worry as I expect the FOV of pancake optics to continue to widen.

OPTICS

The most recent version of VR headsets mostly used Fresnel optics, which offer a wider field of view, but increased distortion. Software calibration is used to offset the distortion, taking up valuable processing power.

The newest versions, like the Pico 4 and Quest Pro, use pancake optics, which employs a strategy of bending the light through multiple curved lens layers. This greatly reduces the distance required between the user’s eyes and the light source, reducing the size of the headset. Pancake lenses also require brighter light as the lenses are multi-layered. But with battery and processor efficiency gains, these trade-offs are manageable now.

DPI AND RESOLUTION

Most of us are used to seeing pixel counts represented, like 1920×1080. But for VR, pixel density is much more important. Apple coined the term “Retina Display” when their LCD screens reached a pixel density so the human eye could no longer perceive individual pixels.

Retinal resolution is 60 pixels per degree, or one arc-minute per pixel. Without getting into how the eye works, if you take the horizontal pixels per eye of the headset, and divide by the field of view, the resulting measurement is the pixel density. The closer this gets to 60, the better the resolution.

The original Oculus DK1 had a 640 (horizontal) x 800 (vertical) display per eye, which is a FOV of 90° for a pixel density of just 7. Remember 60 is the gold standard.

Here is the pixel density of the most common headsets on the market today:

VIVE Focus 3 and Pro 2: 2448×2448 per eye
@ 120° FOV = 20.4
VIVE Pro: 1440×1600 @ 110° FOV = 13
Oculus Quest 2: 1720×1890 @ 96 ° = 17.9
Quest Pro: 1800×1920 @ 106° = 17
Pico Neo 3: 1832×1920 @ 98° = 18.7
Pico 4: 2160×2160 @ 105° = 20.5
HP Reverb G2: 2160×2160 @ 98° = 22
3Glasses: 1440×1440 @ 90° = 16

As you can see, there has been significant improvement in resolution over the last couple of years in pixel density and FOV. Ideally, you’re looking for a balance between both, with the VIVE Focus 3 and Pro 2 leading in this important category.

Resolution is important to the experience in two key areas. In shooting games, accuracy at distance is critical. The poor resolution of early headsets made it difficult to accurately target characters farther away. Another place resolution matters is in escape games, or anything that requires the player to view small controls or readouts. Driving and flying sims are another place where seeing detail at distance matters.

Considering how much modern VR attractions cost, be aware of headset resolution. Consumers now have 4K televisions at home with pixel densities over 100 at typical viewing distances. And ask about upgrade paths, so as pixel density increases over the coming years, you can stay with the times.

DEGREES OF FREEDOM (DOF)

DOF is how we talk about headset tracking. There are 3 DOF and 6 DOF headsets. 3 DOF only tracks head rotation while 6 DOF tracks both rotation and movement in space. The difference is significant. If you wear a 3 DOF headset and lean forward, instead of your perspective shifting in the virtual environment, the entire virtual environment moves with you. Cue barfing.

Many Chinese sims have 3 DOF headsets. Never buy a motion simulator with a 3 DOF headset. In fact, there is no reason to buy a 3 DOF headset at all. They should be reserved for media viewing in a seated static position. The HTC VIVE Flow is an example of a modern 3 DOF headset. It’s designed for things like meditation. For location-based entertainment, stick to 6 DOF.

TRACKING

Tracking technology has advanced to where external cameras are almost a thing of the past. Most modern headsets now have tracking built into the device. This “inside-out” tracking is what you will find in the VIVE Focus 3, Quest 2 and Pro, Neo 3 and Pico 4, and the HP Reverb. The only major headset that doesn’t include inside-out tracking is the VIVE Pro 2, which still relies on Valve Lighthouse cameras.

Most major free-roam VR experiences have dumped the external cameras for inside-out. Zero Latency, Phenomena, and Hero Zone have all gone with the VIVE Focus 3. Spree is using the Pico Neo 3. Where Virtual Rabbids from LAI uses Lighthouse and the VIVE Pro 2, King Kong of Skull Island went with the HP Reverb and inside-out tracking.

Spree is one of the few companies using hybrid tracking systems. The early versions of inside-out tracking suffered from drift. This is when player positions would become less accurate the longer players were in a virtual arena. Over time it became dangerous. New approaches to tracking, using visual anchors like QR codes or other bold graphic objects on the floor and walls, enable headsets to recalibrate themselves continuously.

One advantage of inside-out is that Lighthouse cameras can interfere with one another. A common problem was that FECs running both Hologate and Rabbids would have to position them far away from each other because they both use Lighthouse cameras.

On the downside, inside-out requires a reasonable amount of light, as the cameras use machine vision vs. the infrared lasers of Lighthouse. Despite those limitations, the cost savings and reliability will favor inside-out tracking.

HAND TRACKING

One of the most exciting new developments in VR is hand tracking. At first the purview of a company called Leap Motion (now part of UltraLeap), hand tracking tech has seen major investment from all the major headset manufacturers. Meta is in the lead here, but HTC and Pico are hot on their heels.

Hand tracking tech uses onboard cameras to track and replicate hand movements in VR. It promises new modes of user control, potentially eliminating controllers. I have yet to see any great implementations of hand tracking in arcade games, but I expect to see this develop over the next year or two.

INTERPUPILLARY DISTANCE (IPD)

The distance between the pupils in our eyes varies from person to person. When you get fitted for corrective lenses, the optometrist will measure your IPD to make sure the focal point of the lenses is a perfect fit. Since VR headsets put lenses close to your eyes, the IPD is critical to focus and comfort. Early headsets offered mechanical adjustments to IPD. The latest higher-end HMDs with eye tracking electronically measure and adjust for IPD. This feature will become standard soon.

EYE AND FACE TRACKING

The newest headsets incorporate the ability to track where your eyeballs move, when you blink and raise your eyebrows, and how your mouth moves. Eye or gaze tracking enables something called “foveated rendering”. This is when the HMD intelligently increases the pixel count in the area of focus and decreases the pixels in your peripheral vision. It’s a more efficient use of processing power and has little to no impact on the user experience.

Face tracking lets avatars show emotion and other physical cues for a better sense of presence and connection. For now, they’re being applied to cartoon avatars. But the improvement in technology will bring photorealistic versions that show real emotion, making that sense of presence lifelike.

PASS-THROUGH VIDEO

Another exciting area of development is the ability of headset cameras to show real-time video of the physical environment. This capability enables easier transitions from the real to the virtual worlds. Imagine putting on a headset and still seeing everything around you. It enables players to navigate confidently until they are safely inside the play space, at which point the virtual world takes over.

Other use cases will be to continue play on arcade games. Today if a player wants to go again, they need to take off the headset, find their play card or wallet, and then find the payment peripheral before putting the headset back on. All of that takes time and breaks immersion. Soon, games will switch to passthrough mode so players can swipe their cards and get right back into the action.

Finally, mixed reality is coming. Meta showcased this at their Connect conference in October with the Quest Pro. Mixed reality will add virtual objects into the real world. Think laser tag with real walls, but also virtual robots flying around the room. So far only the Quest Pro offers full color, 3D, low-latency pass-through necessary for this capability. The Pico 4 has full-color pass-through, but only one camera so it’s not 3D. But I suspect within two years this will be a standard feature of most headsets

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