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VR Interfaces: Shutter Glasses


Overview of Shutter Glasses
The human brain perceives depth only because it has two eyes for visual input. Each eye sees a slightly different angle of the same scene (as evidenced when you hold your finger in front of your nose, then look at it with one eye closed, both eyes and the other eye closed ? the image shifts).

These two separate views are combined in the brain to form a single, 3D image, with parts of the data from each eye used to work out relative distances.

To replicate this effect in VR, you require a device that can do the same thing ? give each eye a separate view. Shutter glasses are one method of doing just that.

Shutter glasses work with shutters that switch on and off many times a second, alternating between the eyes. This happens too quickly for your brain to process it, but forces a situation whereby whenever one eye is looking at the display, the other is looking at a black, closed shutter. The shutter glasses and the display system ? monitor, holoprojector, retinal laser etc ? work in tandem, either through wires, or more commonly now, Wi-Fi. The shutter glasses sync their shuttering speed precisely to the refresh rate of the display system, so that the display can show images appropriate to the left and right eyes, at appropriate times.

The first shutter glasses were mechanical in nature, and actually lowered blanking plates in front of each eye, making them heavy, unwieldy, and to hot from friction and power requirements to wear right next to the eyes for very long. These days, most are LCD based, with the liquid crystal screens polarising and thus blanking out at alternate times, making them lightweight, efficient, and plummeting cost.

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