Eye gaze cameras require specific positioning, and consistent access to the user's pupils. Glasses and dry eyes also have the potential to interfere with eye gaze. It may be necessary to recalibrate the ProSlate 13 with Enable Eyes from time to time, especially with significant positioning or ambient lighting changes.
This article will provide some recommendations to ensure the best chances of eye gaze success.
Positioning
User Positioning
- Positioning is key for all AAC users who utilize eye gaze as their access method. To set up for eye gaze, allow the user to sit comfortably and in a relaxed position before positioning the device. Sometimes, people sit up straight to calibrate the device and then return to a different position after calibration is complete; this degrades performance because the person has moved significantly since the time of calibration. Again, please keep in mind: before positioning the device, make sure the user is in a relaxed and comfortable position
Device Positioning
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Angle: The screen of the device needs to be parallel to the plane of the user’s face. If the user is sitting vertically, the device should be vertical. If the user is leaning back, the device should tilt forward to maintain a parallel orientation to the user’s face. A good point of reference, the user’s eyes should be parallel to the top of the device!
- Distance: The ProSlate 13 with Enable Eyes™ should be approximately 20-24 inches from the user.
Troubleshooting Poor Eye Tracking
Poor Camera Focus
- The eyegaze camera will not be able to focus optimally on the user’s eyes if the ProSlate™ is not positioned correctly in front of the user (see above) or if the face plate of the tracker is dirty.
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After making sure that faceplate is clean, reposition the device (move it closer or further from the end user) until the user's eyes (2 green dots) are centered in the indicator box.
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To verify appropriate distance, use the distance indicator. Instructions on how to access this tool can be found in this article: How do I calibrate eye gaze?
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The dark line on the distance indicator symbolizes the user's distance from the camera. The two white lines provide a guide for appropriate distance (ideally the dark line would be between the two white lines).
- The eye animations will be green if the user is an appropriate distance from the camera.
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Common Challenges with Eye Glasses
- Glare Reflections on Glasses: Some users who wear glasses will have glare spots (bright reflection spots) on the lenses of their glasses. To the eye gaze camera, these may look like pupils, which can ultimately confuse the camera. If this is occurring, the circular eye gaze animation will flash or blink on the screen. To correct this, move the device to a different position/angle.
- Highly Reflective Glasses Frames: Sometimes metal-framed or rhinestone/gem glasses that are highly reflective can cause calibration challenges. To the eye gaze camera, rhinestones or reflections may look like pupils, which can ultimately confuse the camera. If this is occurring, the circular eye gaze animation will flash or blink on the screen. To correct this, either move the device to a different position/angle or consider switching to simpler/less reflective frames.
- Scratched or Smudged Lenses: Scratches and smudges on the lenses of the glasses can distort the eye gaze camera's view of the pupils. If this is occurring, the circular eye gaze animation will flash or blink on the screen. Ensure that you are using glasses with clean, clear lenses.
Occluded Pupils
- Eye tracking software relies on seeing the entire roundness of the pupil. If the user’s eyelids are drooping downward and covering the top part of the pupil, tracking quality will degrade. Users who demonstrate eyelid drooping benefit from mounting the device in a slightly higher position.
Medication
- The eye tracker looks for a pupil size within a certain range. If the user’s pupils are under- or oversized due to medication, you could experience intermittent tracking behaviors.
- Those with dry eyes may have difficulty with eye tracking.
Ensure that Snap-to-Item is Turned "On"
For most functions, we recommend that the "Snap to Item" feature is turned on. This feature helps the eye gaze camera to "snap" to available targets on the screen. To verify that this feature is turned on, go to:
- Open "Settings"
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Tap “Accessibility," and then "Touch."
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Select "Assistive Touch."
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Scroll down and select "Devices."
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Select "Hiru."
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Ensure that the "Snap to Item" feature is toggled to "On."
Sometimes, "Snap to Item" can accidentally be toggled off via "Hot Corners," which are shortcuts programmed into the corners of the screen. To turn ensure that "Snap to Item" is not a "Hot Corners" shortcut...
- Go to Settings > Accessibility > Touch > AssistiveTouch (Refer to Steps 1-3 above)
- Select "Hot Corners."
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If one of the shortcuts (Top Left, Top Right, Bottom Left, Bottom Right) is set to "Hot Corners," click on that shortcut and change it to "None."
More about "Hot Corners" can be found here: How do I program Hot Corners?
Our Team at Forbes AAC always wants to ensure that you feel supported! If you need additional assistance, please reach out to your local Assistive Technology Specialist or to our Tech Support Team!
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