Home Forums Eye Tracking Devices fixation jitter Reply To: fixation jitter

Grant [Tobii]

Hi @vwgx3, thanks for the additional information regarding your project intentions. Indeed, I would agree you are quite within the licence agreement so no worries on that point 🙂

So, my overall sense with respect to your ongoing issue is that the method by which you are determining a fixation should be looked at again.

You had not mentioned which SDK you are using, but assuming that you are working with the Tobii Core SDK Interaction API, then it may be of better use to use to use the inbuilt fixation stream .. had you already checked this out?

To make things easier, here is a link to the sample applications for the Core SDK @ https://github.com/Tobii/CoreSDK/tree/master/samples

If you goto ‘streams’ then ‘Interaction_Streams_101’ this provides a simple interface to the fixation data the Core SDK can provide…hopefully it should suffice for your needs. Please let me know your thoughts.

Whilst the delta-position, delta-time route may seem reasonable, in combination with the variable capture rate of the EyeX, I am afraid this is not a sufficiently reliably means of determining a fixation as you have already discovered..hence I would strongly recommend using one of the aforementioned fixation filter algorithms above if the Core SDK fixation stream does not serve.

With regard to the EyeX’s variable capture rate itself, this is in fact due to the hardware and firmware used in producing this consumer level eye tracker. For studies or projects that require a more constant capture rate, we have the Tobii Pro range of trackers which as a consequence are rather more expensive due to the increased sophistication of the internal components.

Hopefully we can get your project and up running soon, thanks for your patience.