Eye tracking Coordinates

[Sarah Kendl]

Hi everyone,

I am doing a student activity at Cornell University for the investigation of commercially available eye-tracking systems. Utilizing the TOBII Core SDK for the TOBII Eye Tracker 4C, we received the following data stream for the fixation data for looking at the bottom right hand corner of the screen;

X: 105.955735579977 Y:348.0055664308

What is the coordinate system utilized for the TOBII Eye Tracker 4C?

It does not seem to match the coordinate system utilized by the TOBII Pro SDK;

http://developer.tobiipro.com/commonconcepts/coordinatesystems.html

Any help would be appreciated.

Thanks,

Sarah Kendl

[Grant [Tobii]]

Hi @sarahkay, thanks for your query. Indeed the fixation co-ordinates reflect the position relative to the maximum pixel dimension of the screen, so a screen at 1024×768 resolution should produce values of that range when looking at the bottom right, which is why your values seem unusual.

Can you run the “Interaction_Streams_102” sample from the Core SDK samples @ https://github.com/Tobii/CoreSDK and report the values returned just to double check? Thanks for your patience whilst we try to resolve your issue.

[Zayn Sk]

Student activities are great initiatives. Good Luck.

[Grant [Tobii]]

Hi @sarahkay, can you kindly confirm that you managed to resolve your issue? Please let us know if we can be of any further assistance. Best Wishes.

[Fred Udoye]

Hi Everyone, I am using Tobii eyetracker. Please how do I find the fixed point in the display (display centre, corner)? Also, if I have two groups of participants viewing images on the screen while their eyes are tracked. How do I find the group centre? Do I get the group centre by calculating the mean of x and y coordinates for that group?

Thank you in advance for your response.

Fred

[Grant [Tobii]]

Hi @fred4 and thanks for your query. A fixed point would be the top left of your screen which represents the value (0,0) of the Eye Gaze Data as reported by Tobii Core SDK and Stream Engine API.

If by Group Centre of users, you mean the screen location (x,y) that receives the most gaze? This would be more dependent on the *time* or fixation duration of the gaze rather than simply the ‘mean’ of gaze locations reported as data will still be sent if the user is not looking at screen but still trackable.

With the Tobii Core SDK, we demonstrate a few examples that demonstrate how to work with Fixation Data @ https://github.com/Tobii/CoreSDK/tree/master/samples/Streams with further information about fixations you can read @ https://tobii.github.io/CoreSDK/articles/streams.html

Please do bear in mind however that using a consumer-level Tobii Tracker (4C, EyeX) for anything other than interaction purposes requires the purchase of a special analytical licence. You can read more about this @ https://analyticaluse.tobii.com/

If you could kindly clarify your Tobii hardware model and corresponding SDK, we would be better placed to help you.
Please do let us know if we can provide any further information.

[Fred Udoye]

Thank you for your suggestions. Much appreciated.

Fred

[Grant [Tobii]]

You are quite welcome! Please do let us know your experiences after trying out our SDK’s and happy coding 🙂

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