nicetoolbox.detectors.feature_detectors.kinematics.velocity_body

Velocity Body feature detector class for kinematics of the body.

Classes

VelocityBody

The VelocityBody class is a feature detector that computes the kinematics component.

class nicetoolbox.detectors.feature_detectors.kinematics.velocity_body.VelocityBody(io, data, sequence_context, algorithm_instance: str)

The VelocityBody class is a feature detector that computes the kinematics component.

The VelocityBody feature detector accepts the human_pose component (body_joints) as its primary input, which is computed using the human_pose method detector. The kinematics component of this feature detector calculates the Euclidean distance between adjacent frames, essentially determining the velocity of body movement from one frame to the next.

Initialize base detector with references.

Subclasses should call super().__init__() and set inference_config.

compute()

Computes the kinematics component.

This method calculates the Euclidean distance between adjacent frames for each keypoint. It handles both 2D and 3D data. The method starts by loading the joint data from the input files. It then computes the differences between adjacent frames for each keypoint. A zero-filled frame is added at the beginning to match the original number of frames. Finally, the Euclidean distance for each keypoint between adjacent frames is computed. The computed differences are stored in a dictionary and saved to a compressed .npz file with the following structure:

• displacement_vector_body_2d: A numpy array containing the computed differences

  for 2D data.

• velocity_body_2d: A numpy array containing the computed velocity for 2D data.

• displacement_vector_body_3d: A numpy array containing the computed differences

  for 3D data.

• velocity_body_3d: A numpy array containing the computed velocity for 3D data.

• data_description: A dictionary containing the data description for all of the

  above output numpy arrays. See the documentation of the output for more details.

Returns:

A dictionary containing the above mentioned parts of the

kinematics component.

Return type:

out_dict (dict)

visualization(out_dict)

Creates visualizations for the computed kinematics component.

This method generates visualizations for the computed kinematics component. It checks if the output dictionary contains the keys ‘velocity_body_2d’ and ‘velocity_body_3d’. If these keys are present, their corresponding values are used to create the visualizations.

The method calculates the sum of movement per body part using the post_compute method. It then determines the global minimum and maximum values to define the y-limits of the graphs. Finally, it calls the visualize_mean_of_motion_magnitude_by_bodypart function from the kinematics_utils module to generate the visualizations.

Parameters:

out_dict (dict) – The output dictionary containing the computed kinematics component. It should contain the keys ‘velocity_body_2d’ and/or ‘velocity_body_3d’.