Six-Doff

If you don’t know what 6DOF means, it’s shorthand for Six Degrees of Freedom — there are the basic six that correspond to the three axes of movement (along X, Y and Z), plus the three axes of rotation (around X, Y and Z). Your mouse, for example, has two: horizontal and vertical (X and Y).

Many pseudo-religious wars have been fought among game and UI designers about the best way to map the mouse’s two limited degrees of freedom to the proper six, using combo buttons and control keys and everything under the sun to make those two act like more. But in reality, it can never work perfectly. Too much thought is involved and users invariably get lost, until they become old pros, and then the software becomes obsolete, meaning UI designers wind up copying older software just because people have gotten used to it, not because it’s better (hence the wars).

What we really need is hardware that has all six degrees of motion, movement and rotation. And until recently, that was just too expensive. I remember using a fairly clunky, rigid strain-gauge device called a SpaceBall in 1994 that cost $3000 and offered no tactile feedback on motions at all. They got the price down to a couple hundred eventually. And finally, 3DConnexion offers a conceptually similar product that costs only $60 for the non-commercial version using optical sensors to make it cheaper and more natural feeling than its ancestors. That price is low enough for it to really take off. Stefan has a review. And I will be buying two.

The Nintendo Wii takes a different approach, putting the sensor in your hand in mid air — the Wiimote. It can also move in all six degrees of freedom, though the precision for some motions may not be high enough for all tasks. The Wii is meant as a gestural device primarily. It can tell what kind of motion you’re doing and how well or strongly you’re doing it. I’ll reserve judgment until I see it applied to CAD. But in theory, a high-precision version of the idea can work there too.

There was a similar product using ultrasound that augmented a standard-looking mouse to let you pick it up and oriented in six DOF. The difference with the Wii is that you could easily use one in each hand (two or four come standard), for an exponential increase in abilities.

The big change from when I started working in VR is now people are genuinely excited. The Wii is a huge hit, partly due to its controller and partly due to its simplicity and ease of use. And that’s going to translate to PCs and virtual worlds sometime soon. Graphics and networking were once bottlenecks, but lately, the user interface has really been the only thing holding virtual worlds back.

The big question is whether 6DOF is enough. I’ve hinted that using both hands is important. Why? For manipulating 3D objects, you want to move, rotate, but also scale and change properties. If one hand is used for precise control, the other can be used for choosing actions. If single handed, you have to drop an object while you go to a menu somewhere and that slows work-flow. Both hands need not be 6DOF necessarily. But I’m curious to see how these 3DConnexion drivers work. I’m guessing they’re meant to work solo, which would be bad for what I have in mind, but not impossible. (the CNET version has the info — it’s meant to be used side-by-side with the mouse, not replacing it, which in this case is good).

By the way, if you’re curious as to what advances this sort of technology allows, consider that the Virtual Jungle Cruise (Disney Ride) was made possible by 6DOF controllers. The challenge there was taking a motion platform made for pre-recorded movies and making it interactive with 3D graphics. And the problem there was that we had four people sit in a rubber raft at once. You’d be hard pressed to find a single steering wheel that works for four people. But four oars in virtual water worked well for collaborative steering. And those oars were enabled by 6DOF controllers taped to each handle (more like the Wii kind, not the 3DConnexion kind).

BTW, with the popularity of the Wii, I’m bracing myself for some young researcher or Nintento patent attorney claiming to have invented collaborative steering controls using 2 or 4 Wiimotes to drive one shared vehicle. That’s more Disney’s problem, as they really hosed my patent application as I was leaving. But memories are short.

Consider also that all of those cool multi-touch displays we’ve seen videos of use two hands. But two hands gives you more than 12 apparent degrees of freedom (depending on how they’re combined, they overlap or augment). It engages your brain a bit differently than just using a mouse. A mouse uses a little bit of our natural proprioception, but the position of the hands relative to our body is really what kicks our natural spatial sense into high gear. The old cybergloves tried to take advantage of this, with moderate success. They not only had 6 degrees per hand, but also had some extra overlapping degrees of freedom from the flexing of the fingers and gestural modes.

Anyway, to make a long story short, what we really need is to kick the mouse off the desktop. A $60 6DOF controller can do that. But it can also spur those who have been waiting for the landscape to shift to move into high gear too. It’ll be as if the ice has melted and summer has finally arrived.

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P.S. the one issue people never seem to address with these controllers is RSI. There is both an advantage and disadvantage to using a mouse in a narrow space. Our wrists can take a lot of repetitive motions better than, say, our backs. But that narrow movement is what induces repetitive motions in the first place. The best thing is to design an input device that avoids repetitive motions and mixes it up a bit over time. 6DOF controllers can be better at that. But now you have to deal with stresses on your shoulder and back from lifting your arm in the air. We’ve already seen injuries from using the Wiimote, mostly collisions, but perhaps some backs or elbows have been wrenched too. We have tennis elbow. I’m guessing we’ll settle on Wii-shoulder, though it could be anything. Still, better to have us moving around than sitting still for 8 hours a day. I’ll be buying a Wii too.

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