Home Forums Software Development Tracking on large screen / user relatively close to screen


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    Paul H

    I have searched through the various posts concerning usage on larger screens and was unable to find the answers I am looking for. I am looking to order the Tobii EyeX Dev Kit. The specification indicates that it can be used with a monitor up to 24 inches. In some instances, I am interested in using the device with a 40 inch monitor where the user will be about 18 to 24 inches away from the monitor. What sort of performance can I expect in this situation? Because the user is sitting relatively close to the monitor the user will likely be moving their head slightly to gaze at the leftmost and rightmost parts of the screen.


    Hi Paul,
    the eye tracker as such isn’t limited to any particular screen size. But the optics are tuned for a distance of about 60-80 cm and to viewing angles that correspond to roughly a 24 inch screen. If you use it with a larger screen you will see that the eye tracking performance gets worse the further the gaze point is from the eye tracker. It can still be useful, though, it depends on what you intend to use it for.

    Another issue with larger screens is that people tend to lean back further to watch them, possibly so far back that they leave the tracking box.

    And finally: head movements are almost never a problem with Tobii eye trackers.



    I’d like some further guidance with regard to larger screens. I have a few questions:

    Does Tobii have any plans to add better support for larger screens to the EyeX drivers (27″ and 30″ are both fairly common sizes among gamers, in my experience) ?

    As you have mentioned, there is an observed lack of accuracy near the top left and top right corners on a larger screen such as 27″ or 30″. I’m looking to rectify this problem. Would it be helpful to position a second Tobii EyeX at the top of the display in an inverted configuration, then use data from the top eye tracker to more accurately determine eye position when the eye is looking near the top of the display? If so, do you have any guidance for such an inverted configuration from a development perspective? I assume the EyeX engine doesn’t support an inverted configuration like this by default, so I assume it would require using the Tobii Gaze SDK?

    If you have any other suggestions or insights for larger displays (are you guys working on different hardware to support this?), I’m all ears. Thanks!

    Mattias [Tobii]

    Hi Andrew,

    I’m sorry to say that your suggestion with an inverted eye-tracker will unfortunately run into a few issues with the EyeX controller, and although the idea does solve some problems it will run into others, in particular practicalites like eye tracker interference and certain eye-tracking algoritms difficulties.

    However, on the positive side, we are continuously working on improving the eye-tracker performance and we have the ambition to make the EyeX controller work better in the corners for larger screens (like 27″). We will continue to update the core algorithms and controller firmware and we will post here if/when we reach a level where we state that we support a larger screen. So for now, not too much guidance, but hopefully a bit of info on what lies ahead.

    Camilo Toro

    Hi Anders;
    Following up on your comments to Paul. From your response, am I correct inferring then that if I preserve the viewing angle (for example, a smaller screen with a closer distance to the screen) I would still get optimal performance?, and if so, is there a limit for proximity…?

    We all seem to have our individualized ideal distance (most comfortable…) to view the screen. I am even wondering if, even when working on large monitors, people would be able to find that ideal distance and execute their human-tobii-pc interactions within that defined 2d space…?



    Hi Camilo,
    the tracker does have a limit for proximity. It’s due to the optics inside. For the REX the operating distance between eye tracker and eye is specified as 40–90 cm and it’s roughly the same for the EyeX controller. That’s a decent size range and of course we hope that it will be sufficient for most users.

    A smaller screen will have near-optimal eye tracking performance everywhere as opposed to a large screen where the performance will degrade the further you get from the tracker.



    Since it’s been a while, is it the same regarding the performance with larger screens(40″) ? Or has it been some development for such applications?


    Grant [Tobii]

    Hi @jbergenstrahle, yes I am afraid for now, the same limitations apply

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