IMPORTANT: Facial Action Coding is a complex routine that requires extra FACS training from a professional in that area.
Our examples will NOT make you a FACS professional. They only show how you can use INTERACT for Facial Action Coding.
This setup was developed to log separate Events per AU in one pass and frame based intensity rating in a second pass.
The Idea
If you want to use the FACS coding-system, to code event-based occurrences per Action Unit with a variable length, and want to add Intensity for some Action Units on a frame-by-frame based separately, a totally different setup is required.
This example describes how you can code 33 discrete Action Units (AUs = muscle movements of the face).
These Events can co-occur, so none of them are mutually exclusive.
When coding occurrences, we begin a coding segment of that AU when it reaches B level intensity, skipping A level intensity events. We close the Event when it falls below a B level intensity.
Some of the Action Units shall be coded for Intensity in a seconds pass. To log the Intensity, we want to take each individually coded Event for such an Action Unit, add a buffer of 10 frames before and after the Event, and then code the intensity level on a frame-by-frame base for the selected Event.
For example, if AU 1 occurs at frames 121-140, we would code the Intensity for frames 111-150 to account for A-level events.
Process description
To implement a FACS coding process following the requirements described, we need a code definition file that holds all required AU-Codes.
To log the occurrences as Events that can overlap, we select the Coding Mode Standard (ad-hoc). Whenever a specific AU activity occurs, we log an Event with the corresponding AU Code.
After logging the AU occurrences, we run a command called Shift Time Values to add 10 frames before and after any number of selected Event lines, all at once.
To rate intensity there are two possible approaches:
 | Frame by frame - Single frame Events can easily be logged with Codes without duration. |
| Fixed intervals of any length - For fixed intervals of more than 1 frame, it is probably easier to split the AU Event. |
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