eye movement based human computer interaction technique
Post on 12-Jul-2015
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TRANSCRIPT
1
Contents• Introduction
• Current Techniques
• Eye Tracking system
• Methods of Measuring
• Applications
• Advantages
• Limitations
• Conclusion
2
Current Interfacing Techniques
• Normal Interface
• Touch Screen
• Voice
• Wave
• Eye movement
3
The Eye
4
• Cornea is a transparentstructure that covers the iris andpupil; a part of the focusingsystem of an eye.
• Pupil is the adjustable openingat the center of the iris thatallows varying amounts of lightto enter the eye.
• Lens helps to focus light on the retina.
• Retina includes rods (94%),which are sensitive to light andcones (6%) that capture colors.Cones are concentrated in thecentre of the retina - the fovea
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
5
Types of Eye Movements• Fixation
• Saccade
• Pursuit
• Tremor
• Rotation
• Drift
6
Methods for Measuring Eye Movements
• Electronic
• Mechanical
• Optical/Video o Single point
o Two point
7
Electronic Method
• The most used method is to place skin electrodes around the eyesand measure the potential differences in eye
• Wide range -- poor accuracy
• Better for relative than absolute eye movements
• Mainly used in neurological diagnosis
8
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
9
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
Optical/Video based Method-two point
11
• 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
Eye Tracking System
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Corneal reflection plus pupil eye tracker
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.
13
Applications
• Automated drug screening.
• Retail advertising effectiveness.
• Surgical Training
• Training and simulation
• Vision Research
14
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.
15
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.
16
Conclusion
• Emerging Interaction Technique
• Eye tracking is far from “perfect”
• show the intensity of the user’s attention
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Any Questions..
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Thank You
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