Not a member yet? Register for full benefits!

VR Interfaces: AirStrike


Overview of AirStrike
AirStrike is a gesture control system designed to enable control of any pc or display interface via waving your fingers in the air, and smart sensing technology to detect those gestures accurately enough to completely replace a computer mouse or 3D pointer. It is not a display technology itself, simply the ability to control displays.

It was born in part, by a desire to prove that touchscreen was not the only way to go. A system that worked like touchscreen but without actually touching the display, would work even where there was no screen to touch; head mounted displays and holograms.

Because it works off of both visible light and the infrared range, it is capable of controlling a liquid droplet hologram system such as Fogscreen or Heliodisplay, where other technologies have failed. This is because water droplets are invisible to infrared light, and do not detract from the detectable finger movements.

Airstrike detects finger movements by way of one or more input strips embedded with two CCDs each. For a PC, that input strip is a normal keyboard with a CCD at either end, for triangulation purposes. However, in larger displays, for general public use, the keys can be foregone in favour of a featureless strip bar sensor.

CCD stands for Charge-coupled device. The type of CCD used by Airstrike is designed to capture and process images, and is functionally identical to the sensor type found in digital cameras. It works by detecting light intensities in its determined optical range. On the top of the CCD there is a photoactive region defined by an array of light sensitive capacitors and a transmission region directly under it.

An image is projected by a lens on the photoactive region, at a rate of several dozen times per second. Each time this occurs, the capacitors electrical charge alters proportional to the light intensity at that location in the snapshot of the world it views. This is essentially a light intensity greyscale digital photograph which the transmission region converts into a pulse stream that can be understood readily by machine vision systems. Two of these CCDs on a bar about 30 cm apart, create two different images of the same area in near-space, which can readily be combined into a stereoscopic image used for exact spatial placements of a user's fingers in 3D space. From this, and from changes in finger position over very short spaces of time, the desired command is inferred and acted upon.

Commands are simple and intuitive. In general the user's finger takes the place of a mouse cursor, and pressing that finger towards the screen signifies a click. However, most interestingly the system is fully capable of using all the fingers on both hands at the same time, to interpret an instruction or set of instructions. That is, as long of course, as the mass of one hand is not obstructing the other from the two CCDs. More units are necessary for a true 3D picture to be constructed, but for most uses, two suffice.

Once an item is selected on the screen, the gesture of grabbing at something in space and pulling it apart or unfolding it, does just that - it zooms an image in, filling up the screen. Virtual environments, paint programs, even complex menu systems can be accessed in this way, without the necessity for a computer mouse at all.

Hopefully we will see more such gesture control systems in the near future, competing with touchscreens.


Untitled Document