Eye movement-based interaction is one of several areas of current research in human computer interaction in which a new interface style seems to be emerging. In the non-command style, the computer passively monitors the user and responds as appropriate, rather than waiting for the user to issue specific commands. In describing eye movement-based human-computer interaction we can see two distinctions, one is in the nature of the user’s eye movements and the other, in the nature of the responses. In the world created by an eye movement based interface, users could move their eyes to scan the scene, just as they would a real world scene, unaffected by the presence of eye tracking equipment movement, on the eye movement axis. The alternative is to instruct users of the eye movement based interface to move their eyes in particular ways. On the response axis, objects could respond to a user’s eye movements in a natural way that is, the object responds to the user’s looking in the same way real objects do. The alternative is unnatural response, where objects respond in ways not experienced in the real world. Now a days Eye tracking technology is applied in many fields like automotive defense and medical industries. The fields of advertising, entertainment, packaging and web design have all benefited significantly from studying the visual behavior of the consumer. Every day, as eye tracking is used in creative new ways, the list of applications grows.

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2. Contents
• Introduction
• Current Techniques
• Eye Tracking system
• Methods of Measuring
• Applications
• Advantages
• Limitations
• Conclusion
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3. Current Interfacing
Techniques
• Normal Interface
• Touch Screen
• Voice
• Wave
• Eye movement
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4. The Eye
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• Cornea is a transparent
structure that covers the iris and
pupil; a part of the focusing
system of an eye.
• Pupil is the adjustable opening
at the center of the iris that
allows varying amounts of light
to enter the eye.
• Lens helps to focus light on the
retina.
• Retina includes rods (94%),
which are sensitive to light and
cones (6%) that capture colors.
Cones are concentrated in the
centre of the retina - the fovea

5. Vision Field
• Vision field is divided in to three regions
o Fovea provides the sharpest vision
o Parafovea previews foveal information
o Peripheral vision reacts to flashing objects and sudden
movements
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6. Types of Eye Movements
• Fixation
• Saccade
• Pursuit
• Tremor
• Rotation
• Drift
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7. Methods for Measuring
Eye Movements
• Electronic
• Mechanical
• Optical/Video
o Single point
o Two point
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8. Electronic Method
• The most used method is to place
skin electrodes around the eyes
and measure the potential
differences in eye
• Wide range -- poor accuracy
• Better for relative than absolute eye
movements
• Mainly used in neurological
diagnosis
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9. Mechanical Method
• Based on contact lenses
with
o mirror planes + reflecting
IR-light
o coil + magnetic field
• Very accurate
• Very uncomfortable for
users who are not used to
wear lenses
o Usable only for lab
studies
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10. Optical/Video based
Method-single point
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• Tracking one visible feature of the
eyeball, e.g.:
o limbus (bondary of sclera and iris)
o pupil
• A video camera observes one of
the user's eyes
• Image processing software
analyzes the video image and
traces the tracked feature
• Based on calibration, the system
determines where the user is
currently looking
• Head movements not allowed
o Bite bar or head rest is needed

11. Optical/Video based
Method-two point
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• The same idea as in the single point
method except now two features of
eye are tracked – typically
o corneal reflection
o pupil
• Uses IR light (invisible to human eye)
to
o produce corneal reflection
o cause bright or dark pupil, which
helps the system to recognize pupil
from video image
Bright pupil
Corneal reflection

12. Eye Tracking System
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Corneal reflection plus pupil eye tracker

13. Cont…
• Corneal reflection plus pupil eye tracker
• The pupil camera and illuminator operate along the
same optical axis
• Servo controlled mirror is used to compensate for
the user’s head motions.
• tracks the corneal reflection from an infrared light
shining on eye and the outline of the pupil
illuminated by same light.
• Computes the visual line of eye gaze by relationship
between two tracked points.
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14. Applications
• Automated drug screening.
• Retail advertising effectiveness.
• Surgical Training
• Training and simulation
• Vision Research
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15. Advantages
• Eye movement is faster than other current input
media.
• No training or particular coordination is required of
normal users.
• Can determine where the user’s interest is focused
automatically.
• Helpful for usability studies to understand users
interact with their environments.
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16. Limitations
• Equipment is expensive
• Some users can't work with the equipment (if they
wear contact lenses or have long eye lashes)
• Moving one's eyes is often an almost subconscious
act.
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17. Conclusion
• Emerging Interaction Technique
• Eye tracking is far from “perfect”
• show the intensity of the user’s attention
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18. Any Questions..
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19. Thank You
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