I am trying to do something similar with Tobii 4c using the Tobii Stream Engine in linux. I was using my personal calibration method, but it is not that accurate and I thought of using the custom calibration with tobii API. I have seen that there is a function called tobii_calibration_collect_data_3d, which is exactly what I want to use, but I see that the units for z coordinate is in mm, and I will use distance further (1~5 meters, which is like 5000mm). I am not sure if this distance is suitable for tobii calibration. Moreover, do you have any sample code for calibration? I managed to stream gaze data, however, when I run the function tobii_calibration_start, i will get error all the time.
I would appreciate if you could help me with that! Thank you