How to properly discard failed calibration points

[Adrián]

Hi! We have a calibration implemented in our .NET application using tobiistreamengine and we have some doubts about what is the correct way to discard a point that has failed. If we get an error after running tobii_calibration_collect_data_2d(), we save that point coordinates to a list. After we have evaluated all the points in the screen, we run tobii_calibration_compute_and_apply(). Next, we iterate through the failed points and run tobii_calibration_discard_data_2d() on them. Then we try again to collect the data from the failed points and finally we run tobii_calibration_compute_and_apply() again.

Should we discard the failed points with tobii_calibration_discard_data_2d() before executing tobii_calibration_compute_and_apply()?

Thanks!

PS: It would be great if the tobiistreamengine API could be completed with more examples. 🙂

[Jonas Högström]

Unless you use the partially calibrated gaze data after the first call to compute_and_apply, there is no need to call it. you can remove the failed points immediately and re-collect them before calling compute_and_apply.

The call to collect_data_2d can fail for different reasons. The most common reason is probably that not enough samples were collected. That doesn’t have to mean that the collected samples are bad. If you discard them and collect new data at the same coordinate, there is a risk that also the second collect will not yield enough samples, but together it might be sufficient. If you have reason to believe that the data that was collected was bad (includes eye movements, or user was looking elsewhere), it is correct to discard the data.

[Adrián]

Thanks for your quick reply, Jonas. It was really helpful.

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