Standalone or Wide field-of-view HMD? (HoloLens vs. Meta2)
July 1, 2016 - Dr.ir. Dragos Datcu, Principal Researcher Augmented Reality
Up to date, two of the most promising Head Mounted Displays (HMDs) for Augmented Reality (AR), are Microsoft HoloLens and Meta2. The two (still experimental) optical see-through HMDs have similar appearance and (presumably also similar weights – no full specs available). Several technical characteristics of the two are comparable, yet there are few major differences one has to consider to determine which HMD is more appropriate for a given scenario.
In short, HoloLens has a small field-of-view (FOV) but it already incorporates a 32-bit computer in the HMD (2GB RAM + 1GB RAM for the Microsoft Holographic Processing Unit). Meta2’s has better optics featuring an impressively large screen FOV, but has no processing unit.
HoloLens platform is powerful enough to support the whole human computer interaction, including the data processing and the (3D) visualization. HoloLens features good user tracking in the physical environment and accurate interaction with the augmented content, allowing to pin windows of running apps directly on surfaces from the physical environment (like walls). HoloLens benefits from Universal Windows Platform (UWP) protocol-based apps via Windows Store. Consequently, apps like Outlook Mail and Calendar gets adapted and are just made available to run on the wall-sized holographic display.
Even though HoloLens’ hardware was tailored to run smoothly in most of the cases, the fixed built-in computing platform represents a big limitation for more complex scenarios.
On the other hand, Meta2 HMD does not include any computer – it is just an external (very good) AR visualization device. On one hand this aspect represents a big drawback, because another (mobile/heavy and powerful/expensive) computer has to do all the work, and because the HMD cable connecting Meta2 to the computer limits the mobility and the interaction in AR. The effects are even more significant, especially when the user wearing Meta2 HMD walks freely outside, pursuing AR-based productive or entertainment activities. On the other hand, the fact that Meta2 HMD accepts any computer to boost AR sessions, means any future, lighter, more-powerful mobile computer can enhance the capabilities of an existing Meta2 HMD and so can extend its use duration. For Meta2, the pixels density – the number of pixels per degree is presumably half (estimated, no complete specs) than for HoloLens.
In May Microsoft Research proposed a lower tech solution to augment HoloLens’ low field of view and to greatly improve the situational awareness and user experience. This was presented at a top-level conference on Human-Computer Interaction (ACM CHI 2016). The solution is based on sparse peripheral displays (inexpensive array of lightweight, low-resolution LEDs) surrounding the central high-resolution display, and is shown to expand the field-of view up to 190-degree horizontal.
Choosing between the two AR HMDs depends on the budget and on the scenario the device will target. Meta2 can be an option if one already has a powerful computer around. More, the Meta2 HMD leads to higher flexibility, allowing for future upgrades on the computer so that it runs more complex, more demanding apps and new interaction capabilities.
Both platforms are excellent for researchers and for hobbyists. Apart from them, companies have to propose AR HMD-based solutions easy to monetize, to identify realistic production or entertaining scenarios that are appropriate for the capabilities of the current and yet-to come consumer AR HMDs. Microsoft HoloLens is more like a mobile, ready-to-go, full-solution AR HMD, while Meta2 is an excellent external visualization HMD providing higher immersion in AR. This is just another (essential) intermediary step towards future AR technologies which will enhance our everyday live. Meta already announced that they aim for standalone, non-tethered AR HMDs for the future. The competition steadily increases, with players coming and going and most importantly, with the consumer to take advantage on truly amazing advancements of the AR technology.
- self-contained, standalone computer (Intel 32 bit CPU and custom-built Microsoft Holographic Processing Unit, passive cooling) running on Windows 10
- UWP (Universal Windows Platform), cross platform capabilities, great support for apps from Windows Store, etc.
- great AR tracking, good user experience that allows to pin apps directly on physical walls
- no cables
- game streaming feature of Xbox One (useful especially for playing AAA games)
- universal recharging cable (the HMD is functional while recharging)
- fixed hardware
- small field-of-view
- human interaction support: spatial sound, gaze tracking, gesture input, voice support
- memory: 64GB Flash, 64GB Flash
- sensors: 1 IMU, 4 environment understanding cameras, 1 depth camera, 1 2MP photo/HD video camera, mixed reality capture, 4 microphones, 1 ambient light sensor
- connectivity: Wi-Fi 802.11ac, Bluetooth 4.1 LE, Micro USB 2.0
- battery life: 2-3 hours (active use), up to 2 weeks (standby)
- weigh: 579 grams
- Price: $3,000 (June 30, 2016)
- Large field-of-view
- Interaction: Clicker enables selection, scrolling, holding, and double-clicking during extended, interactive scenarios.
- Cable-driven (9-foot HDMI 1.4b) for video, data and power
- Tethered device, requires additional powerful computer (Windows 8 or 10)
- field of view: 90-degree (diagonal)
- display resolution: 2560 x 1440 pixels (1280×1440 pixels per eye)
- sensors: Sensor array (for hand interactions and positional tracking), 6-axis inertial measurement unit
- camera: 720p front-facing camera
- weight: 420 grams (without head straps)
- Price: $949 (June 30, 2016)
Discussion and Comparison
- Both are optical see though Head Mounted Displays (HMDs)
- They have similar form factor design and appearance, and presumably similar weight
- Both HMDs have capabilities for remote collaboration in AR
- Both are experimental devices (for development only)
- Meta 2 design is newer than HoloLens
- field of view: Meta2 (90-degree – excellent, almost the same as Samsung Gear VR 96-degree) – that is better than for HoloLens (not specified exactly). Meta2 provides higher immersion in AR, and more natural interaction support
- HoloLens is a self-contained computer while Meta2 is just a visualization-only HMD; the price is naturally higher for HoloLens
- HoloLens is already shipping, Meta2 takes pre-orders and starts shipping in Q3 2016