Home Forums Software Development NaN data from GazeDataRecieved!!

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    I am receiving gaze data that, for a series of sequential GazeData points, all values are NaN.

    I would like to know what that implies about those data points, as compared to times when i am receiving no data from the tobii at all.

    It seems like it would make sense that the tobii is not reporting any gaze data(even empty) when if cannot ‘see’ any eyes to track, and all NaN entries would imply it ‘sees’ some sort of eyes but is unable to determine gaze data for them.

    What i’m driving at is: what’s the difference between receiving no GazeData(not even an empty object) when you would expect a datapoint to come in via GazeDataReceived, and receiving the GazeData but all the values are NaN.

    A caveat is i’m adapting from legacy software with low confidence. If tobii is initialized correctly, should it always broadcast GazeData even if it cannot register a viewer? The old software would report nothing if there was no person in front of the tracker, and i’m unsure if that is how the tobii operates or something in the legacy app that is swallowing the ’empty’ data points.

    I’m using a 4C Tracker with the Pro SDK in .Net
    – if i’m in the wrong place please for the love of god tell me where I supposed to ask this because I’ve tried twice now and i’m perpetually in the wrong place.

    Grant [Tobii]

    Hi @tigamendonza, sorry to hear about your troubles. Unfortunately, as you are using a Tobii Eye Tracker from the Tobii Tech Business unit in conjunction with an SDK from the Tobii Pro Business it does complicate the issue of the correct team to speak to, but I will try to offer what advice seems relevant.

    In general, NaN values may be produced when the Eye Tracker is connected properly, but there is some issue in capturing the eyes, either due to blinking, strong sources of infrared light nearby (open Windows, spotlights, etc) heavy makeup, facial piercings, etc or simply when the user is outside the range of the tracker itself.

    Assuming you check the environmental conditions are properly adjusted, then I would recommend you perform a test over a couple of minutes by focusing your gaze over a number of pre-defined points (say 4: one at each extreme) on the screen, ensuring the gaze never leaves the monitor area.

    Have a look at the resultant output. If the Data contains a significant amount of NaN values, this would indicate either some environmental condition or issues with the user themselves and so would recommend you to run the test again on another user.

    For cases where No GazeData (not even an empty object) when expecting a datapoint to come in via GazeDataReceived: This could indicate a possible hardware or connection issue however I would investigate all these options first and report back. Again would be useful to know what fraction of the total output we are dealing with here.

    Something also worth trying is to run these screen test program using the Tobii Core SDK which is in fact designed for operation with the 4C. It would be interesting to see if the same NaN/NoData issue persists or not.

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