MHT with Remote Optics

EYEHEAD integration is the combining of eyetracking with head tracking.

By combining the Model R6 remote optics with a magnetic head tracker you can eliminate the need to reacquire the eye when the subject looks out of the covered area or makes a fast or jerky head movement. The ASL software uses the head position data to control the pan tilt on the remote camera for immediate reacquisition. This is an indispensable feature when working with infants or any subject where you can not continually monitor.

EYEHEAD Integration with Head Mounted Optics

EYEHEAD integration is necessary to obtain digital data that specifies point of gaze with respect to stationary objects in the environment. The EYEHEAD integration package, for use with head mounted optics enables integration of eye and head position data to compute real time point of regard. Required hardware includes a magnetic head tracker and a gimbal and laser pointer (left).

EYEHEAD Environment

The EYEHEAD "environment" consists of the magnetic head tracker transmitter and up to 20 surfaces of interest. Typical surfaces include monitor screens, keyboards, poster displays, slide screens, walls, etc. EYEHEAD data consists of the identification number of the scene surface being viewed, coordinates of the gaze point on that surface, the distance of the eye from the spot being fixated and pupil diameter. Note that this information does indicate what the subject is viewing in the environment.

What are the advantages to the ASL system when combined with a magnetic head tracker?

REMOTE PAN/TILT

	Enables pan tilt module to follow the eye whenever the subject is within a trackable space without any intervention from operator
	Much more robust eye tracking with less restraint on subject
	Operator never has to manually aim pan tilt module
	Automatic reacquisition if subject moves out of tracking area
	Automatic reacquisition after quick/jerky head movements
	Corrects for geometrical error introduced by change in head position
	Improves accuracy of data in presence of head motion

HEAD MOUNTED

	Computes the location of the gaze vector in true 3 dimensional space
	Determines intersection of gaze with multiple flat surfaces whose location, orientation and boundaries are known in true 3D space
	Surfaces are easily specified to system using a laser pointing device (3 points define a surface)
	Can accurately superimpose a point of gaze cursor on the image from a stationary (non-head mounted) scene camera. Most systems can only superimpose a cursor on a head mounted scene camera image.
	Better image than head mounted camera
	Less to wear on the head
	One less thing to set up and adjust

The Ascension Magnetic Head Tracking System is available through ASL. Contact us for options and pricing.

ASL currently has interfaces with Ascension, Polhemus and Intersense head tracking systems. Other interfaces can be developed upon request.

All pictures on this page feature the Ascension Flock of Birds magnetic head tracking system.