Activity Tracking#
The activity tracking module processes camera frame events to compute motion activity or motion energy within a specified region of interest. This measure of general activity is particularly useful for distinguishing between periods of static inactivity (such as sleep) and static activity (such as grooming).
Nodes#
ActivityTracking#
The ActivityTracking (Aeon.Vision) node accepts frame events generated by a camera and is used to compute motion activity or motion energy within a region of interest.
Specifically, background subtraction is performed on the input camera frames based on a single frame history. The raw sum of absolute pixel intensity changes is then computed.
Inputs#
None
Outputs#
A stream of Harp.Timestamped<double> describing the raw absolute differences in pixel intensity of consecutive frames within the region of interest.
Properties#
General#
Property name |
Description |
|---|---|
Region |
An array of four |
ThresholdValue |
The lower threshold for pixel intensity differences to be included in the sum activity. Should be set to the pixel noise |
Subjects#
Events from the node are published to a Subject, the name of which is configured in the properties of the node. This Subject then becomes accessible in the Bonsai editor’s toolbox and is useable elsewhere in the workflow using the same name.
Device event subjects#
Subject name |
Type |
Description |
|---|---|---|
TrackingEvents |
|
The |
Usage#
Create a GroupWorkflow.
Inside, place an ActivityTracking (Aeon.Vision) node and connect it to the WorkflowOutput.
Using a SubscribeSubject, e.g. “CameraTop”, subscribe to the target camera’s “FrameEvents” Subject and connect it to the ActivityTracking node.
As with InRange (Aeon.Acquisition), more than one region of interest can be defined using multiple GroupWorkflows, each containing a separate instance of ActivityTracking (Aeon.Vision).