As part of my previously-mentioned Second Life-ish semi-addiction, I bought a 3Dconnexion SpaceNavigator 3D mouse. It’s a $60 USB device about the size of a small fist, with a heavy bottom and a manipulatable knob. It supports three axes of spatial rotation plus movement in three dimensions. That is to say you can pitch, roll, yaw, move up/down, left/right and forward/backward, or any combination of these at the same time. For example, grab the knob and pull up to rise. To lower while barrel rolling to the right, push down on the knob while applying rotational pressure to the right. You basically have six axes to play with. (Yes, I know dimensional movements aren’t considered axes, but just drink the Sony kool-aid for a moment.)
The Second Life client (and any client based off it, such as the Hippo OpenSim Viewer) natively supports the SpaceNavigator, and supports three modes. While in normal avatar mode, it controls your avatar: dimensional movement to walk/fly around, and roll/pitch/yaw to control where you look. When in edit mode, the SpaceNavigator controls the movement and rotation of the object being manipulated. Personally, I don’t like using the SpaceNavigator for either of these modes. Movement with the SpaceNavigator is OK, but can get tiring pretty quickly. Yes, physically tiring. You’re actually applying a significant amount of pressure to get it to do what you want it to do, and it can wear down your hand pretty quickly. As for building, using the SpaceNavigator is way too imprecise. More often than not, building is a much more mathematical objective than just moving stuff around. I would like an option to be able to use the SpaceNavigator while in build mode so I could manipulate the camera relative to the object, but that functionality does not appear to exist.
The third mode is where it really shines. Press the left button on the SpaceNavigator, and the SL client goes into Flycam mode. The camera is now detached from the avatar, and you now have complete control over the movement and rotation of the camera. This is what you can do with almost no practice:
That video was controlled entirely by the SpaceNavigator in Flycam mode, and was basically me tooling around Undef Lagoon randomly. One thing I should point out is that in that video, you’ll notice that I was going forward at a constant pace while moving around. You’d be tempted to think that Flycam mode operates like a plane, with constant thrust, but no, I had my thumb pushing forward on the knob for most of it. Toward the end I do fly backwards for a bit. It’s also a bit easier to understand the controls in this next video I made, as it starts out with a pull-back, while moving up and pitching down:
That video had a bit more jerky movement, because as I said, it takes a fair amount of pressure to manipulate the SpaceNavigator. So if you’re not going full-bore (as I was throughout most of the first video), it’s harder to maintain a constant pressure. Still, it has a lot of potential for machinima, and is just plain fun to use.