RE: eye gaze human computer interface
THE EYEGAZE COMMUNICATION SYSTEM (1).doc (Size: 209.5 KB / Downloads: 177)
The Eyegaze System is a communication and control system for people with complex physical disabilities. You run the system with your eyes. By looking at control keys displayed on a screen, a person can synthesize speech, control his environment (lights, appliances, etc.), type, operate a telephone, run computer software, operate a computer mouse, and access the Internet and e-mail. Eyegaze Systems are being used to write books, attend school and enhance the quality of life of people with disabilities all over the world.
Imagine yourself being a intelligent, motivated, and working person in the fiercely competitive market of information technology, but just one problem You can't use your hands. Or you can't speak. How do you do your job? How do you stay employed? You can, because of a very good gift from computer Industry : The Eyegaze, a communication & control system you run with your eyes.
The Eyegaze System is a direct-select vision-controlled communication and control system. It was developed in Fairfax, Virginia, by LC Technologies, Inc.,
Who's using the Eyegaze System?
This system is mainly developed for those who lack the use of their hands or voice. Only requirements to operate the Eyegaze are control of at least one eye with good vision & ability to keep head fairly still. Eyegaze Systems are in use around the world. Its users are adults and children with cerebral palsy, spinal cord injuries, brain injuries, ALS, multiple sclerosis, brainstem strokes, muscular dystrophy, and Werdnig Hoffman syndrome. Eyegaze Systems are being used in homes, offices, schools, hospitals, and long term care facilities. By looking at control keys displayed on a screen, a person can synthesize speech, control his environment (lights, appliances, etc.), type, operate a telephone, run computer software, operate a computer mouse, and access the Internet and e-mail. Eyegaze Systems are being used to write books, attend school and enhance the quality of life of people with disabilities all over the world.
2.1The skills needed by the user :
2.1.1 Good control of one eye : The user must be able to look up, down, left and right. He must be able to fix his gaze on all areas of a 15-inch screen that is about 24 inches in front of his face. He must be able to focus on one spot for at least 1/2 second.
• Several common eye movement problems may interfere with Eyegaze use. These include:
Nystagmus (constant, involuntary movement of the eyeball):
The user may not be able to fix his gaze long enough to make eyegaze selections.
Alternating strabismus (eyes cannot be directed to the same object, either one deviates):
The Eyegaze System is constantly tracking the same single eye. If, for example, a user with alternating strabismus is operating the Eyegaze System with the right eye, and that eye begins to deviate, the left eye will take over and focus on the screen. The Eyegaze camera, however, will continue to take pictures of the right eye, and the System will not be able to determine where the user's left eye is focused. When the left eye deviates and the right eye is again fixed on the screen the Eyegaze System will resume predicting the gazepoint. Putting a partial eye patch over the nasal side of the eye not being observed by the camera often solves this tracking problem. Since only the unpatched eye can the screen, it will continuously focus on the screen. By applying only a nasal-side patch to the other eye, the user will retain peripheral vision on that side.
2.1.2 Adequate vision:
Several common vision problems may affect a user's ability to see text clearly on the Eyegaze monitor. These include the following:
Inadequate Visual acuity:
The user must be able to see text on the screen clearly. If, prior to his injury or the onset of his illness he wore glasses, he may need corrective lenses to operate the Eyegaze System. If he's over 40 years old and has not had his vision checked recently, he might need reading glasses in order to see the screen clearly.
In most cases, eyetracking works well with glasses. The calibration procedure accommodates for the refractive properties of most lenses. Hard-line bifocals can be a problem if the lens boundary splits the image of the pupil, making it difficult for the system's image processing software to determine the pupil center accurately. Graded bifocals, however, typically do not interfere with eyetracking.
Soft contact lenses that cover all or most of the cornea generally work well with the Eyegaze System. The corneal reflection is obtained from the contact lens surface rather than the cornea itself. Small, hard contacts can interfere, if the lens moves around considerably on the cornea and causes the corneal reflection to move across the discontinuity between the contact lens and the cornea.
Diplopia (double vision):
Diplopia may be the result of an injury to the brain, or a side effect of many commonly prescribed medications, and may make it difficult for the user to fix his gaze on a given point. Partially patching the eye not being tracked may alleviate double vision during Eyegaze System operation.
Another occurrence associated with some brain injuries, as well as a side effect of medications, a blurred image on the screen decreases the accuracy of eye fixations.
Cataracts (clouding of the lens of the eye):
If a cataract has formed on the portion of the lens that covers the pupil, it may prevent light from passing through the pupil to reflect off the retina. Without a good retinal reflection the Eyegaze System cannot accurately predict the user's eye fixations. The clouded lens may also make it difficult for a user to see text on the screen clearly. Surgical removal of the cataracts will normally solve the problem and make Eyegaze use possible.
Homonymous hemianopsia (blindness or defective vision in the right or left halves of the visual fields of both eyes):
This may make calibration almost impossible if the user cannot see calibration points on one side of the screen.