Change Gaze Trace Behavior?

[Adithi Deborah Chakravarthy]

I am trying to program an App where the user is required to focus on an object on screen while tracing a line using the mouse. An error message pops up whenever the user is out of focus. Since the gaze trace is extremely sensitive, I am met with constant error message – I would like to either decrease the sensitivity of the gaze trace or increase the radius around it in the focus. Looking forward to suggestions on the same.

[Grant [Tobii]]

Hi @adithideborah and thanks for your query. Could you kindly clarify what you mean by “out of focus” … you mean an error when the user is no longer tracked?

That being the case, instead of generating an error on the first loss of tracking, you could keep a counter that will only show the error after a certain threshold amount of time has passed without tracking. Would this serve your needs? In any event, if you could be more explicit with the project description, we will do our best to help you out. Best Wishes.

[Adithi Deborah Chakravarthy]

Thank you for the response. Yes, right now I have a delay timer which throws an alert when user gaze is no longer on focus object (out of focus). I was wondering if there were other approaches. I am building an app for elderly patients to trace lines while focusing on an onscreen object/point which will be used by medical experts to correlate with disease. Right now alert messages are thrown very frequently since the object they are to focus on is smaller than the gaze trace bubble which appears on screen. Hence I was wondering if there was some way to tweak its sensitivity or radius to handle this.

[Grant [Tobii]]

Hi @adithideborah, okay thanks for the clarification. The radius of the gaze trace (at rest) in fact represents the minimum area of accuracy whilst tracking which is a function of biology (small movements of gaze do not change eye position) rather than technological limitations of the tracker so is not something that can be ‘reduced’ per se. In any event, it would be beneficial to increase your stimulus size to accommodate this minimum tracking area if possible.

[Adithi Deborah Chakravarthy]

Thank you for the response. Increasing the size of the stimulus (further at this point) actually defies the purpose of the eye trials. So I was wondering if there was anything that I could do from the technological end.

[Grant [Tobii]]

Hi @adithideborah no I’m afraid the gaze trace output shows the minimum tracking size and so is not subject to customisation in the manner you specified. Hopefully you can still continue with your project without too much issue. Please let us know if we can be of any further assistance.

[Adithi Deborah Chakravarthy]

Thank you. Can the trace behavior be changed to track only one eye instead of both? My application also involves patients performing certain tasks with one eye closed. Even the OnGaze() function seems to consider loss of eye signal (when i blink) as out of gaze.

[Grant [Tobii]]

Hi @adithideborah, unfortunately monocular tracking is only available with the Tobii Pro SDK, which requires the purchase of a special unlock file to operate with the Tobii 4C (or EyeX) tracker. If you would like a quote, feel free to send your project specifications to [email protected] and the team there will get back to you.

Regarding your project itself, please kindly be aware that the Core SDK and Tobii Tech range of eye trackers (4C, EyeX) are intended for interaction purposes only.
Any use of this software and hardware to perform analysis requires the purchase of a special analytical use licence to do so.
You can read further information about this @ https://analyticaluse.tobii.com/

[Adithi Deborah Chakravarthy]

I do have the Tobii Pro SDK with EyeX. Does monocular tracking work by default or do any changes need to be made to calibration/code to perform this?

[Grant [Tobii]]

Hi @adithideborah, great! Yes monocular tracking should work by default as each individual eye gaze co-ordinate is exposed within the Pro SDK.

That being said, this forum is principally intended for support with the Tobii Tech range of trackers and associated SDK’s. I would therefore recommend you contact Tobii Pro Support directly @ https://connect.tobiipro.com/s/?language=en_US and the team there will be best placed to assist you further.

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