Tracking the eye movement in a WPF application

[Aditya Gundawar]

Hello,
My colleague and I are developing an application to track the eye movement in a WPF application using the Tobii 4C eye-tracker.
We have followed the instructions given on the Core SDK page for this eye tracker but the points provided by the gaze stream API are different than the points on the screen which are being looked at.
Is there any calibration mode in 4C that can be used?

[Grant [Tobii]]

Hi @aditya-gundawar, thanks for your query. In order to run a calibration, you will need to launch this from the Tobii System Tray Icon using our own Interaction Software. Certainly, a calibration is essential for each new profile.

You should be able to check the calibration accuracy using the Tray Icon under ‘improve calibration’ on your user profile. Could you confirm that the accuracy is OK and how does it relate to your Core SDK output? Recall that gaze co-ordinates in Core SDK are provided in relative terms from (0,0) to (1,1) so you will need to multiply the results by the monitor resolution to obtain the data in pixels.

If you could kindly provide further details in your reply, we will do our best to assist you further. Best Wishes.

[Aditya Gundawar]

Hi,
Thank you for replying to our query.
We are using this function – “gazePointDataStream.GazePoint((gazePointX, gazePointY, _))”. This function is returning us negative values and values up to 1200, 800. We are using a screen with 1920 x 1080 resolution.

[Grant [Tobii]]

Hi @aditya-gundawar, do you have another monitor attached? Please ensure that you run the setup guide after installing the Tobii Software to correctly associate the eye tracker to the proper monitor. Is the tracker working normally using the Core Software? For example, a game or mouse warp feature?

[Aditya Gundawar]

Hello,
We aren’t using another monitor. We are using a laptop screen of resolution 1920 x 1080. After installing the appropriate software for Tobii 4C, we followed the setup guide and used the in-built calibration tool to calibrate for our laptop screen.
The eye tracker is working properly for the in built game and the gaze stream feature which comes with the software. Using the Core SDK which we have installed using NuGet package manager for WPF applications, we are using this function – “gazePointDataStream.GazePoint((gazePointX, gazePointY, _))” which is not returning values between (0,0) and (1,1) but returning values that seem to be similar to the pixel locations on the screen which also are not that accurate.

[Grant [Tobii]]

Hi @aditya-gundawar, okay thanks for the clarification. As a testing ground, could you kindly run the streams sample application @ https://github.com/tobiitech/core-sdk-docs/tree/master/samples/Streams which can provide the gaze locations in a couple of formats and let us know if the values are still erroneous.

[Aditya Gundawar]

Hello,
Using the link you have provided above, we tried all the 3 kinds of streams available. The “CreateGazePointDataStream” and “CreateFixationDataStream” provide us with erroneous values. The maximum value given by each of these streams are – (1280,800) whereas the monitor resolution is 1920×1080. These streams, as you can see are not giving us values between (-1, 1) as well.
Are there any particular steps that need to be followed to make these streams give their output in the correct range?

[Grant [Tobii]]

Hi @aditya-gundawar, thanks for getting back to use.. that is indeed quite unusual.. you had already stated that the tracker is accurate on the Core software, so it’s not a question of calibration. I wonder if you can adjust your DPI setting on the system to 100%… also, try a different resolution on the monitor to see if that makes any change.

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