CastAR works (and is differentiated from other AR technologies we've seen) using high-resolution micro-projectors that throw content out in front of you, rather than shooting it straight back into your eye.
They key to seeing that content is a retro-reflective material capable of bouncing light back to your eyes. You see what your brain perceives out in space, rather than information presented on a screen close to your face.
Consequently, you're less likely to experience eye strain with castAR, allowing you to use the glasses for longer periods of time. And because you can see the augmented reality content and the physical world at the same time, it's possible to interact with people and objects around you while wearing the glasses. Technical Illusions designed castAR to fit over regular prescription frames, and claims that the final version will weigh less than 100 grams.
Of equal importance is castAR's tracking system, which lets you alter your perspective of the 3D content in front of you. By moving your head around, you can look over the top, from the side, or behind a scene. CastAR registers your movements using a built-in camera that tracks an IR LED marker placed within the field of view of the space you’re projecting onto.
Technical Illusions claims castAR’s positional tracking is sub-millimeter-accurate. Naturally, that accuracy plays a big part in creating an immersive experience. By the time castAR is ready for production, it's expected to employ gyroscopic tracking for use without the IR marker; this is one of the features added through a stretch goal on Kickstarter.
Of course, there also needs to be a way for you to interact with the content projected out in front of you, and there are a number of ways to achieve this. For a more traditional experience, which is one of the demos we tried, you can simply use a game controller. However, Technical Illusions is also working on what it calls the Magic Wand, a 3D input device that uses the same tracking system as the glasses.
Another optional accessory is an RFID Tracking Grid, which sits under the retro-reflective surface. This grid is designed for playing digital board and roleplaying games, and it lets you use objects present in the virtual world. Think D&D miniatures in a projected dungeon. Unfortunately, we weren’t able to test the wand or RFID grid during our time with castAR.
Finally, you'll be able to interact with what you see through gestures. While Technical Illusions isn’t building its own gesture recognition technology, the company told us that castAR will eventually work with commercially available solutions like Kinect and Leap Motion.
The last piece of the castAR system is the AR & VR Clip-on, which converts the glasses from projected AR to more a more traditional AR (or even full VR) experience. The reflective surface on the clip-on bounces the stereo image back to your eyes. This could be particularly useful for when a retro-reflective surface isn't handy.
Of course, you still need the IR tracker nearby in order to take advantage of the precise tracking provided by the glasses' camera. The AR & VR Clip-on wasn’t quite ready for us to test, but Technical Illusions claims that, with it, “you will have no need for any other head-mounted display”.