Knowledge Base

Processors: Boolean and Temporal

Not

This processor has a single Boolean value as input (for instance, a condition that is either True or False) and a single Boolean value as output. If the input is True, the output is False and vice versa.

If.. Else..

An If.. Else block has three inputs: (1) Condition C (left connector); (2) Numerical value A (top connector); (3) Numerical value B (bottom connector). The output is A if C is True and B if C is False. The screen shot below is part of the definition of the Custom Expression 'Duchenne smile'. The output of the If.. Else.. processor is the average intensity value of Action Unit 12 and Action Unit 6 if Action Unit 6 AND Action Unit 12 are active (that is, have both an intensity value higher than 0.2). The output is 0.2 if one or both Action Units are not active.

Temporal

The temporal processors are identical to their non-temporal counterparts except for the temporal aspect. The temporal processors calculate the (weighted) average/sum/maximum/minimum over the time (duration) you specify. You can also specify the minimum percentage of valid samples required to produce a valid output. You can use the temporal processors if your custom expression cannot be determined based on a single point in time and requires a history. For the running processors you cannot set any parameters.

• Temporal Average — This processor calculates the average of its numerical input values over the specified time.
• Temporal Weighted Average — This processor calculates a weighted average of its numerical input values over the specified time. Older results weigh less than more recent results.
• Temporal Standard Deviation — This processor calculates the standard deviation of its numerical input values over the specified time.
• Temporal First Derivative — This processor calculates the rate of change over the specified time. The output is (value of the last valid frame - value of first valid frame)/duration.
• Temporal Sum — This processor calculates the sum of all its numerical input values over the specified time.
• Temporal Maximum — This processor compares two or more numerical input values. The output is the highest value.
• Temporal Minimum — This processor compares two or more numerical input values. The output is the lowest value.
• Temporal Counter — This processor counts the number of times an input value crosses a given threshold in a specified direction.
• Running Average — This processor calculates the average value over all previous valid samples.
• Running Maximum — This processor calculates the maximum value of all previous valid samples.
• Running Minimum — This processor calculates the minimum value of all previous valid samples.
• Running Counter — This processor counts the total number of times an input value crosses a given threshold in a specified direction from the beginning of the analysis.

Miscellaneous

• Constant Value — Use this processor for instance in combination with a Condition to compare the intensity value of an Action Unit with the constant value. See 'Condition' for an example.
• Unknown — Use this processor to give a custom expression the value 'Unknown'. In the screenshot below we defined a custom expression that only gives a value if Action Unit 43 has intensity = 1. In the example, the intensity of AU43 < 1. That means that the condition is false and that the output of the If/else processor is B (Unknown).
• Pi (π) — The number pi (≈ 3.14159) is a mathematical constant, the ratio of a circle's circumference to its diameter.
• e — The number e (Euler's number, ≈ 2.71828) is a mathematical constant.

Tip: Click on a processor to read the information that comes with it. Each processor comes with a description and information on what type of input it can have, what the output will be and what parameters you can define.

Source: FaceReader 10 Reference Manual (Help), Noldus Information Technology