When it comes to describing the different methods and technologies of displaying virtual content, most people by now are familiar with the terms AR and VR, of course meaning Augmented and Virtual Reality.
Microsoft decided to coin yet another phrase when presenting the Microsoft HoloLens: they use Mixed Reality – abbreviated to MR – as a term for displaying virtual content in a way that it’s blended with the real world. In contrast to Augmented Reality (see here) the technology enables you to have your hands free, as it is realized by a see-through goggle.
Currently, the most advanced device on the market enabling this technology is the HoloLens, although other companies – for example Magic Leap or Meta – are developing similar hardware. And as regularly rumored, Apple is surely working on something in this direction, too.
By the way, the famous Google Glass presented a few years ago uses a different approach: It’s simply superimposing translucent popups showing relevant information, but not mixing the content with the real world. So, even if it kind of paved the way to Mixed Reality, Google Glass is not an MR device.
In March 2016 Microsoft released a pre-production version of the HoloLens, at that time targeted to developers in the United States and Canada, expanding to global availability in November. Even though marketed and sold with a lot of „buzz“ by Microsoft, the current version of the HoloLens is still a Development Edition. A Commercial Suite is also available, but that’s the identical hardware plus a warranty and some enterprise (software) features for added security and device management. So talking about the HoloLens means talking about a „work-in-progress“ hardware with some technical limitations.
What the HoloLens can do (at the moment)
The HoloLens is quite a unique device:
First of all, it is completely mobile. There is no need for a cable connection and the device has all its hardware in it. You need to charge it after about two hours of usage, though.
Looking through the HoloLens you are able to place virtual content in the room and walk around or interact with it. This can look like in the promotional video by Microsoft which you can watch here.
The virtual content is placed and tracked very accurately in the real world. As the HoloLens continuously scans the world around it, it can also virtually interact with it. For example, a hole in the wall can open up and show a virtual world behind it.
The HoloLens „remembers“ the scanned area, so you are able to leave a room and come back while all the virtual content stays in the same place. This also enables multiple user with several HoloLenses to see the same virtual content at the exact same position in the real world.
For the virtual content itself, the sky is the limit. With our knowledge and experience, we at unexpected are able to show almost anything you can imagine through the HoloLens.
What the HoloLens cannot do (at the moment)
The HoloLens is a very cool device, but, as mentioned, it still is the Development Edition.
One of the main restrictions is its very small field of view. This is due to several hardware limitations that of course will be minimized in the future, but at the moment it feels like looking at a „transparent window“ in front of you, through which you can see the virtual content around you. All the content next to this „window“ is invisible. (This is called „clipping“.) Luckily, your brain seems to kind of adapt to this and mentally „expand“ the visible area for you the longer you use the HoloLens.
Another limitation is the complexity of 3D objects, concerning to some degree the polygon count, but especially shading and lighting. However, as we know this limitation, we can keep it in mind when working on the data, so we are able to create content that looks well without making any trouble.