Strapping tiny computers to your face is popular enough now that it's easy to lump Technical Illusions' CastAR augmented-reality glasses in with Google Glass, the Oculus Rift and other high-tech eyewear.

But doing so does the CastAR a disservice. I tested a CastAR prototype on the show floor at GDC Next, and when the final version ships next year I think it will provide a significantly different experience than either Google Glass or the Rift. Rather than intruding into your vision or taking over it entirely, CastAR creators Jeri Ellsworth and Rick Johnson designed their glasses to only overlay the digital world atop the real one when you choose to look at specific sheets of retro-reflective material.

It's a small but critical difference. The CastAR glasses are much less nauseating than the Rift dev kit, because you can see objects in the real world and thus maintain your balance and equilibrium while you're moving your head around. Ellsworth and Johnson built these glasses to play 3D games without throwing up in the process, but after putting the prototype through its paces I think this hardware has the potential to change the way we look at spreadsheets, web browsers, and all kinds of software beyond the gaming sphere.

Augmented reality so bright, you've gotta wear shades

The experience of using the CastAR glasses is hard to describe; if you've ever looked at the world through a pair of active-shutter 3D glasses, it's sort of like that. The difference is that the CastAR frames have a pair of LCD micro-projectors mounted on top of the frame, one over each eye.

Each projects a slightly offset version of the same image at 1280-by-720 resolution, and if you look at a special piece of material you'll see a shimmering three-dimensional scene reflected back at you. The images are piped to the glasses via HDMI from a nearby PC, and that plus the power required to run the glasses means we probably won't see a wireless version anytime soon.

Games running on the CastAR look a bit like the holographic chess game from Star Wars, except that instead of projecting out of the board the images projected by the CastAR appear to move around inside the material. If you've ever watched a 3D movie where the simulated depth stretched into the screen instead of jumping out at you, looking at CastAR software looks very similar.

How it works

The retro-reflective material that makes the CastAR system work looks like nothing so much as a swath of grey construction paper--until you look at it with a pair of active CastAR glasses. It's very similar to the reflective material you see on road signs and safety vests, it's incredibly cheap and you can arrange it however you like. Plus, since the material reflects the light directly back at your eyes it's possible to have multiple people wearing CastAR glasses looking at the same sheet of material and seeing completely different scenes.

The obvious use for this stuff is to cover a table or game board with it, but you can also hang it up on walls, lay it on the floor or arrange it anywhere you want to create an augmented-reality screen. While testing the CastAR prototype I played a game with multiple sheets of material on the table, the walls and the floor, and I found that peeking around or under a table in real time and see digital phantasms leaping around on the walls and floors is a surprisingly unsettling experience. You can control CastAR software using anything that hooks into your PC, including gesture controllers like the Leap Motion, which could lead to some intriguing Minority Report-style software that lets you flip and move through 3D interfaces.

When you move your head while wearing the CastAR glasses the images displayed on the sheets will adjust to match your perspective--you can walk around a 3D model to view it from different angles, or move your head closer to the surface to zoom in on images. It's a neat trick made possible by a tiny tracking camera on the bridge of the glasses that tracks your head movement in 3D space using infrared markers in the world around you. Ellsworth claims this tracking system is far more accurate than the gyroscopes used by headsets like the Rift.

The idea is to build these tracking markers into products that use the reflective material, such that you could have a game board or a poster-sized sheet on the wall with sensors built into the corners. When I tested the CastAR there was only one IR tracking marker on the table and thus it was possible to muck up the visor by blocking line-of-sight between the CastAR's tracking camera and the IR marker, but having multiple markers in the room should alleviate that problem when the CastAR becomes available next year.

You can get your hands on a prototype version of the CastAR glasses by backing their ongoings Kickstarter to the tune of $900, but I can't recommend you do so unless you've a vested interest in developing augmented-reality software. The developer prototype should be even smaller than the version I tested at GDC, but it won't be as light or comfortable as the finished product--which is projected to weigh less than a quarter of a pound--and there won't be much in the way of software--games or otherwise--available. The final version is expected to launch late next year at a projected price of $189, and by that point there should hopefully be a broad array of augmented-reality software available that supports the CastAR.