What are some calibration tips for eyetracking?
•Knowing your client is very important
−Visual affect – left, right, top or bottom
−Visual ability – one or both eyes
•Know what your client wants to accomplish
−If your client wants to do Windows control and computer access, a higher quality calibration is likely needed.
−If your client is using simple, big button AAC pages, a lower quality calibration may suffice.
•Know how you can make the experience better
−Calibration Points – 1, 2, 5 or 9
−Calibration Area – it can be adjusted to make calibrating easier
−Stimulus Type – dot, image, or video
−Stimulus Size – making the dot larger makes it easier to see and focus on
−Stimulus Speed can be adjusted
−Keyboard Step Through – allows an aide to step through the calibration points when the end user is ready/attentive
−Improve/Remove Points – this option allows for fine tuning of points without redoing the entire calibration
What are we looking for from the calibration results?
•Lots of lines
•Short and within the circles
If we do not get that…
•Check the calibration points and select the ones that need to be redone
•Choose improve points and have the client look at those
•Use fewer calibration points or change stimulus to make it easier
- Raising the device higher resolves many issues with calibrating successfully or improving calibration results.
- In the calibration results, identify the targets that have the longest whiskers. Most people’s instinct is to select those targets and choose Improve Points. If no changes have been made to resolve the issue, simply improving the points may not provide different results.
- Once the targets that need improvement are identified, determine if there is a pattern. For example, do the targets on the bottom row contain the worst results? If so, change the calibration area so that the calibration points do not reside so low on the screen.
- Stimulus Speed is another factor that may cause poor results. Some individuals cannot follow the target if it goes too fast. Others can’t keep their gaze on the target long enough if the speed is too slow. It is important to get that feedback from the user, if possible.
- Changing the stimulus type can help people keep their attention on the target as well. For example, many children like using the Cat image as their stimulus type.