Reference for ultralytics/trackers/bot_sort.py
Note
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ultralytics.trackers.bot_sort.BOTrack
Bases: STrack
An extended version of the STrack class for YOLOv8, adding object tracking features.
This class extends the STrack class to include additional functionalities for object tracking, such as feature smoothing, Kalman filter prediction, and reactivation of tracks.
Attributes:
Name | Type | Description |
---|---|---|
shared_kalman |
KalmanFilterXYWH
|
A shared Kalman filter for all instances of BOTrack. |
smooth_feat |
ndarray
|
Smoothed feature vector. |
curr_feat |
ndarray
|
Current feature vector. |
features |
deque
|
A deque to store feature vectors with a maximum length defined by |
alpha |
float
|
Smoothing factor for the exponential moving average of features. |
mean |
ndarray
|
The mean state of the Kalman filter. |
covariance |
ndarray
|
The covariance matrix of the Kalman filter. |
Methods:
Name | Description |
---|---|
update_features |
Update features vector and smooth it using exponential moving average. |
predict |
Predicts the mean and covariance using Kalman filter. |
re_activate |
Reactivates a track with updated features and optionally new ID. |
update |
Update the YOLOv8 instance with new track and frame ID. |
tlwh |
Property that gets the current position in tlwh format |
multi_predict |
Predicts the mean and covariance of multiple object tracks using shared Kalman filter. |
convert_coords |
Converts tlwh bounding box coordinates to xywh format. |
tlwh_to_xywh |
Convert bounding box to xywh format |
Examples:
Create a BOTrack instance and update its features
>>> bo_track = BOTrack(tlwh=[100, 50, 80, 40], score=0.9, cls=1, feat=np.random.rand(128))
>>> bo_track.predict()
>>> new_track = BOTrack(tlwh=[110, 60, 80, 40], score=0.85, cls=1, feat=np.random.rand(128))
>>> bo_track.update(new_track, frame_id=2)
Parameters:
Name | Type | Description | Default |
---|---|---|---|
tlwh |
ndarray
|
Bounding box coordinates in tlwh format (top left x, top left y, width, height). |
required |
score |
float
|
Confidence score of the detection. |
required |
cls |
int
|
Class ID of the detected object. |
required |
feat |
ndarray | None
|
Feature vector associated with the detection. |
None
|
feat_history |
int
|
Maximum length of the feature history deque. |
50
|
Examples:
Initialize a BOTrack object with bounding box, score, class ID, and feature vector
>>> tlwh = np.array([100, 50, 80, 120])
>>> score = 0.9
>>> cls = 1
>>> feat = np.random.rand(128)
>>> bo_track = BOTrack(tlwh, score, cls, feat)
Source code in ultralytics/trackers/bot_sort.py
tlwh
property
Returns the current bounding box position in (top left x, top left y, width, height)
format.
convert_coords
multi_predict
staticmethod
Predicts the mean and covariance for multiple object tracks using a shared Kalman filter.
Source code in ultralytics/trackers/bot_sort.py
predict
Predicts the object's future state using the Kalman filter to update its mean and covariance.
Source code in ultralytics/trackers/bot_sort.py
re_activate
Reactivates a track with updated features and optionally assigns a new ID.
Source code in ultralytics/trackers/bot_sort.py
tlwh_to_xywh
staticmethod
Convert bounding box from tlwh (top-left-width-height) to xywh (center-x-center-y-width-height) format.
update
Updates the YOLOv8 instance with new track information and the current frame ID.
Source code in ultralytics/trackers/bot_sort.py
update_features
Update the feature vector and apply exponential moving average smoothing.
Source code in ultralytics/trackers/bot_sort.py
ultralytics.trackers.bot_sort.BOTSORT
Bases: BYTETracker
An extended version of the BYTETracker class for YOLOv8, designed for object tracking with ReID and GMC algorithm.
Attributes:
Name | Type | Description |
---|---|---|
proximity_thresh |
float
|
Threshold for spatial proximity (IoU) between tracks and detections. |
appearance_thresh |
float
|
Threshold for appearance similarity (ReID embeddings) between tracks and detections. |
encoder |
Any
|
Object to handle ReID embeddings, set to None if ReID is not enabled. |
gmc |
GMC
|
An instance of the GMC algorithm for data association. |
args |
Any
|
Parsed command-line arguments containing tracking parameters. |
Methods:
Name | Description |
---|---|
get_kalmanfilter |
Returns an instance of KalmanFilterXYWH for object tracking. |
init_track |
Initialize track with detections, scores, and classes. |
get_dists |
Get distances between tracks and detections using IoU and (optionally) ReID. |
multi_predict |
Predict and track multiple objects with YOLOv8 model. |
Examples:
Initialize BOTSORT and process detections
>>> bot_sort = BOTSORT(args, frame_rate=30)
>>> bot_sort.init_track(dets, scores, cls, img)
>>> bot_sort.multi_predict(tracks)
Note
The class is designed to work with the YOLOv8 object detection model and supports ReID only if enabled via args.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
args |
object
|
Parsed command-line arguments containing tracking parameters. |
required |
frame_rate |
int
|
Frame rate of the video being processed. |
30
|
Examples:
Initialize BOTSORT with command-line arguments and a specified frame rate:
Source code in ultralytics/trackers/bot_sort.py
get_dists
Calculates distances between tracks and detections using IoU and optionally ReID embeddings.
Source code in ultralytics/trackers/bot_sort.py
get_kalmanfilter
Returns an instance of KalmanFilterXYWH for predicting and updating object states in the tracking process.
init_track
Initialize object tracks using detection bounding boxes, scores, class labels, and optional ReID features.
Source code in ultralytics/trackers/bot_sort.py
multi_predict
Predicts the mean and covariance of multiple object tracks using a shared Kalman filter.
reset
Resets the BOTSORT tracker to its initial state, clearing all tracked objects and internal states.