In our experience, many eyetrackers do not have a fixed latency between triggering and data output, whcih can make it tricky to accurately synchronise data streams. To overcome, this we use a 'Data Combination' method, as described in our overview.
The ODIN software suite provides a function that allows time series data produced on a third party device to be imported into a trial after the trial has been completed. An unlimited number of columns of data can be imported within the time series, and individual data can be delimited with a number of different delimiter characters (e.g. comma separated etc.) One of the channels in the time series data must contain a synchronisation signal, generally a 'clapperboard' pulse that allows the ODIN software to align the incoming data with the data already in the trial.
This 'Data Combination' method is generally used for third party devices where there is a variable latency in their data stream output, and/or no reliable digital trigger is available. In the experimental set up, the Codamotion system sends a signal, generally a small pulse, that can be recorded on one of the sensor or auxiliary channels of the third party device (for example, the eye-tracker data stream). The Codamotion software can later use this recorded signal to synchronise the time series data of the third party device with its own recorded 3D data. This need only be done one time. Once a trial is 'locked' together by this Data Combination method, it becomes a single data file.
For data from an eye-tracker to be combined in this fashion, it needs only to provide the following features:
- The ability to record a trigger pulse sent by the Codamotion system on one channel of its time series data.
- The ability to export a time series data file of recorded data with a suitable delimiter separating data points.