Hi @willmccaff and thanks for your query. With respect to Nan reported in fixation location, this indeed can be caused by gaze data either falling out of tracking range or that the eye movement itself was sufficiently erratic so as to not qualify as a true ‘fixation’. for example if you look rapidly from one screen edge to another, this will not be calculated as a fixation. One way to have a look exactly as to what is happening is to analyse the raw gaze data locations as reported by the SDK as see how they look over time. This should allow you to determine what might be the issue. Certainly, if the eye gaze focus is steady within a relatively small area on screen, you should receive valid co-ordinates for fixation.
Regarding custom calibration, you are Correct that this may be implemented in the Stream Engine API however this requires the purchase of a special custom calibration licence to do so. You can request a quote for this by email the licencing team directly at [email protected]
Please have a look at your gaze data and report back here so we can continue to help you in resolving any issue that might be present. Best Wishes.