Figure 2

BonZeb inherits Bonsai's reactive architecture for processing data streams. (A) A video

source node generates images over time. The video source can either be a continuous stream of images from an online camera device or a previously acquired video with a fixed number of frames. A series of transformation nodes are then applied to the original source sequence. Each transformation node performs an operation on the upstream observable sequence that is then passed to downstream nodes. A typical pipeline consists of background subtraction, centroid calculation, tail point calculation, and finally, tail angle calculation. Nodes have a unique set of visualizers that provide the node’s output at each step. Each node has a set of properties associated with the output, such as a single coordinate, an array of coordinates, or an array of angles, which can be used for more sophisticated pipelines. (B) Bonsai workflow implementation of the above data processing pipeline. An additional node is attached at the end of the workflow to save the tail angles data to a csv file on disk. There are 4 different general classifications of nodes in Bonsai. Source nodes (green) generate new observable sequences and do not require inputs from upstream nodes. Transform nodes (blue) perform an operation on the elements of an upstream observable sequence to produce a new observable sequence that can be subscribed to by downstream nodes. Sink nodes (purple) perform side operations with the elements of the data stream, such as saving data to disk or triggering an external device. Sink nodes then pass along the upstream observable sequence to subscribed downstream nodes without modifying any of the elements of the upstream observable sequence. Combinator nodes (not shown here) are important for combining sequences and become crucial for more complex pipelines (see online manual for examples).