2016 has been the year of spending a lot of money to put huge plastic visors on your head. The Google Daydream View, HTC Vive, Oculus Rift, and Sony PlayStation VR are all competing for your wallet, and Microsoft has announced a slew of Windows 10-ready VR headsets on top of them. Microsoft also made its HoloLens available to developers. While the HoloLens seems similar to the other headsets, however, the parallels are entirely superficial. The former are virtual reality headsets, while latter is an augmented reality headset. Here’s the difference.
Virtual reality headsets completely take over your vision to give you the impression that you’re somewhere else. The Vive and Rift displays are opaque, blocking out your surroundings when you wear them. If you put them on when they’re turned off, you might think you’re blindfolded.
When the headsets turn on, however, the OLED panels inside are refracted by the lenses to completely fill your field of vision with whatever is being display. It could be a game, a 360-degree video, or just the virtual space of the Oculus and SteamVR interfaces. Visually, you’re taken to wherever the headsets want you to go—the outside world is replaced with a virtual one.
Many VR games and apps rely on you staying in a fixed position, either sitting or standing, so you don’t walk into walls or knock over things. Because the headsets block out your view (and you’re tethered to your computer through them, in some cases), that’s a significant danger.
The HTC Vive somewhat gets around this by letting you set up a specific VR area. Two external sensors track the headset’s position, and the SteamVR software uses those sensors to map out (with your guidance) a square of empty floor it designates as safe to move in. If you try to move beyond that square, a virtual wall fades into view, letting you know you’re about to move into a space you might not have cleared. It’s a helpful feature that allows limited motion, which opens up some SteamVR games to incorporate actually moving your body around instead of just your head.
The upcoming Windows 10 VR headsets hope to get around the need for external sensors by building outward-facing sensors inside the device itself to track the environment.
The immersiveness of virtual reality can make you want to move your hands around and expect them to appear in whatever software you’re using, but that’s almost never the case. Both the Rift and Vive rely on peripherals for control, and without them you can’t actually interact with anything. They might be as simple as a gamepad or as complex as the HTC Vive’s motion controllers. Even the phone-based Samsung Gear VR has a touchpad on the side to let you control apps. There have been experiments with motion-sensing gloves for VR, but they haven’t picked up any traction outside of research yet.
As touched on, for both games and apps, virtual reality completely supersedes your surroundings, taking you to other places. Where you are physically doesn’t matter. In games, you might sit in the cockpit of a starfighter like in EVE: Valkyrie. In apps, you might virtually tour distant locations as if you were there. There are tons of possibilities in virtual reality, and they all involve replacing everything around you with something else.
Whereas virtual reality replaces your vision, augmented reality adds to it. AR devices like the HoloLens Development Edition are transparent, letting you see everything in front of you as if you are wearing a weak pair of sunglasses. The technology is designed for completely free movement.
Microsoft calls the HoloLens “mixed reality” rather than augmented reality. Academically the term mixed reality refers to the technology behind both virtual and augmented reality in a very broad sense, and Microsoft’s use of it seems based on giving the HoloLens a more uniquely branded identity than anything else. The HoloLens is an augmented reality device, and we’ll refer to it as such.
The HoloLens uses a pair of small projectors aimed at angled lenses built into the visor. The lenses reflect that light while still letting the light of your surroundings pass through, superimposing the projectors’ images on top of your view. Any image the HoloLens displays appears to float in front of you.
The projectors work in conjunction with a series of cameras built into the visor and Microsoft’s “holographic processing unit” (HPU) to track your location in relation to where the holograms are virtually placed. The visor constantly scans any surrounding walls or furniture to map out the space around you, and moves the holograms it displays to reflect how you move. This lets you place a hologram in the middle of the room and walk around it as if it were physically there. You can also walk through that hologram, because of course it isn’t actually in the room; it fades out when you get very close to it, and reappears when you turn around to face it from the other angle.
This technology has a distinct disadvantage compared with virtual reality. While VR completely covers and replaces your field of vision, the HoloLens display only takes up a limited space in front of you. The projectors and lenses are arranged to produce bright, crisp holograms in a rectangular area in the center of your field of vision. When you move your head, the holograms disappear as soon as they hit the edge of the rectangle, making them vanish well before they reach the edge of your vision. Hopefully Microsoft will overcome this limitation as it further develops the HoloLens, because the visual drop-off is the most jarring and disappointing issue with the device.
The primary way to interact with the HoloLens is with hand gestures. The cameras on the device can track your hand and finger movements, and use them to perform different functions. The Bloom gesture of opening your upward-pointed hand opens the Start menu and lets you access the HoloLens’ software. The Air Tap gesture of pinching your fingers together functions as a click. This is gesture-based control rather than perfect movement tracking; you need to master holding your arm at the right distance directly in front of you for the gesture to register, and you can’t simply grab and move holograms quickly with natural actions.
You can use the included Clicker peripheral as well, but it only emulates the Air Tap gesture; it doesn’t function as its own air mouse for precise control. You can also pair a Bluetooth keyboard with the HoloLens for text input.
For apps, augmented reality has nearly limitless possibilities. The HoloLens already projects standard Windows 10 apps as floating windows you can place anywhere around you, effectively giving you an instantly modular multi-monitor computing setup. Other apps, like Holo Studio and HoloPlanner, let you place three-dimensional holograms about your surroundings. Holo Studio lets you create your own holographic dioramas, while HoloPlanner lets you see what your room would look like with difference pieces of furniture places around it.
For games, augmented reality can build experiences using your surroundings. The detective game Fragments scans your room and creates crime scenes based on its layout, placing various set pieces around and producing a slightly different experience with each room. RoboRaid detects where the walls are and projects holograms of robotic arms breaking through them and robots pouring out. Young Conker places obstacles all over your furniture, assembling its levels from your surroundings. In all of these cases, the games change to fit the space.
Virtual reality and augmented reality accomplish two very different things in two very different ways, despite the similar designs of the devices themselves. VR replaces reality, taking you somewhere else. AR adds to reality, projecting information on top of what you’re already seeing. They’re both powerful technologies that have yet to make their mark with consumers, but show a lot of promise. They can completely change how we use computers in the future, but whether one or both will succeed is anyone’s guess right now.