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Eye Tap

Abstract: An Eye Tapis a device that is worn in f ront of theeyethat acts as a camera to record the scene

available to the eye as well as a display to superimpose a computer-generated imagery on the origi nal scene

available to the eye. Th is structure all ows the user' s eye to operate as both a monitor and a camera as the Eye tap

in takes the worl d around i t and augments the image the user sees all owing it to overl ay computer-generated data

over top of the normal worl d the user would perceive. The Eye tap is a hard technol ogy to categori ze under the

three main headers for wearable computing (constancy, augmentation, mediation) for whil e it i s in theory a

constancy technol ogy in natur e it also has the abil ity to augment and mediate the reality the user perceives.

I n order to captu re what the eye is seeing as accur ately as possible, an Eye tap uses a beam spli tter to send the

same scene (wi th reduced intensity) to both the eye and a camera. The camera then digiti zes the refl ected image

of the scene and sends it to a computer. The computer pr ocesses the image and then sends it to a projector . The

proj ector sends the image to the other side of the beam split ter so that th is computer -generated image is reflected

in to the eye to be superimposed on the ori ginal scene. Stereo Eye taps modif y li ght passing through both eyes, but

many research prototypes (mainl y for reasons of ease of constructi on) onl y tap one eye.

Introduction:

Eye tap is a device which allows, in a sense, the eye itself to function as both a display and a camera. Eye tap is at

once the eye piece that displays computer information to the user and a device which allows the computer to process

and possibly alter what the user sees. That which the user looks at is processed by the Eye tap. This allows the Eye

tap to, under computer control, augment, diminish, or otherwise alter a user's visual perception of their environment,

which creates a Computer Mediated Reality. Furthermore, ideally, Eye tap displays computer-generated information

at the appropriate focal distance, and tonal range. The figure below depicts and describes the basic functional

principle of Eye tap. Note from the diagram that the rays of light from the environment are collinear with the rays of

light entering the eye (denoted by the dotted lines) which are generated by a device known as the aremac. "aremac"

is the word camera spelled backwards and is the device which generates a synthetic ray of light which is collinear

with an incoming ray of light. Ideally, the aremac will generate rays of light to form an image which appears to be

spatially aligned, and appears at with the same focus as the real world scene.

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Conclusion

By contrast, in Eye tap devices, the diverter (which may be a double-sided mirror or a beamsplitter) places the centre

of projection of the camera at (in an optical sense) the centre of projection of the lens of an eye of the wearer. When

no computer mediation is used, Eye tap video can be displayed to the user in such a way that the user perceives what

he/she would otherwise have in the absence of the device. Eye tap mediates a portion of the user's vision, in such a

way that it is integrated with the un-mediated portion of the user's field of view, without any mismatch between the

mediated area and the real world.