Reference for ultralytics/trackers/bot_sort.py

def convert_coords(self, tlwh: np.ndarray) -> np.ndarray:
    """Convert tlwh bounding box coordinates to xywh format."""
    return self.tlwh_to_xywh(tlwh)

@staticmethod
def multi_predict(stracks: List["BOTrack"]) -> None:
    """Predict the mean and covariance for multiple object tracks using a shared Kalman filter."""
    if len(stracks) <= 0:
        return
    multi_mean = np.asarray([st.mean.copy() for st in stracks])
    multi_covariance = np.asarray([st.covariance for st in stracks])
    for i, st in enumerate(stracks):
        if st.state != TrackState.Tracked:
            multi_mean[i][6] = 0
            multi_mean[i][7] = 0
    multi_mean, multi_covariance = BOTrack.shared_kalman.multi_predict(multi_mean, multi_covariance)
    for i, (mean, cov) in enumerate(zip(multi_mean, multi_covariance)):
        stracks[i].mean = mean
        stracks[i].covariance = cov

def predict(self) -> None:
    """Predict the object's future state using the Kalman filter to update its mean and covariance."""
    mean_state = self.mean.copy()
    if self.state != TrackState.Tracked:
        mean_state[6] = 0
        mean_state[7] = 0

    self.mean, self.covariance = self.kalman_filter.predict(mean_state, self.covariance)

def re_activate(self, new_track: "BOTrack", frame_id: int, new_id: bool = False) -> None:
    """Reactivate a track with updated features and optionally assign a new ID."""
    if new_track.curr_feat is not None:
        self.update_features(new_track.curr_feat)
    super().re_activate(new_track, frame_id, new_id)

@staticmethod
def tlwh_to_xywh(tlwh: np.ndarray) -> np.ndarray:
    """Convert bounding box from tlwh (top-left-width-height) to xywh (center-x-center-y-width-height) format."""
    ret = np.asarray(tlwh).copy()
    ret[:2] += ret[2:] / 2
    return ret

def update(self, new_track: "BOTrack", frame_id: int) -> None:
    """Update the track with new detection information and the current frame ID."""
    if new_track.curr_feat is not None:
        self.update_features(new_track.curr_feat)
    super().update(new_track, frame_id)

def update_features(self, feat: np.ndarray) -> None:
    """Update the feature vector and apply exponential moving average smoothing."""
    feat /= np.linalg.norm(feat)
    self.curr_feat = feat
    if self.smooth_feat is None:
        self.smooth_feat = feat
    else:
        self.smooth_feat = self.alpha * self.smooth_feat + (1 - self.alpha) * feat
    self.features.append(feat)
    self.smooth_feat /= np.linalg.norm(self.smooth_feat)

def get_dists(self, tracks: List[BOTrack], detections: List[BOTrack]) -> np.ndarray:
    """Calculate distances between tracks and detections using IoU and optionally ReID embeddings."""
    dists = matching.iou_distance(tracks, detections)
    dists_mask = dists > (1 - self.proximity_thresh)

    if self.args.fuse_score:
        dists = matching.fuse_score(dists, detections)

    if self.args.with_reid and self.encoder is not None:
        emb_dists = matching.embedding_distance(tracks, detections) / 2.0
        emb_dists[emb_dists > (1 - self.appearance_thresh)] = 1.0
        emb_dists[dists_mask] = 1.0
        dists = np.minimum(dists, emb_dists)
    return dists

def get_kalmanfilter(self) -> KalmanFilterXYWH:
    """Return an instance of KalmanFilterXYWH for predicting and updating object states in the tracking process."""
    return KalmanFilterXYWH()

def init_track(
    self, dets: np.ndarray, scores: np.ndarray, cls: np.ndarray, img: Optional[np.ndarray] = None
) -> List[BOTrack]:
    """Initialize object tracks using detection bounding boxes, scores, class labels, and optional ReID features."""
    if len(dets) == 0:
        return []
    if self.args.with_reid and self.encoder is not None:
        features_keep = self.encoder(img, dets)
        return [BOTrack(xyxy, s, c, f) for (xyxy, s, c, f) in zip(dets, scores, cls, features_keep)]  # detections
    else:
        return [BOTrack(xyxy, s, c) for (xyxy, s, c) in zip(dets, scores, cls)]  # detections

def multi_predict(self, tracks: List[BOTrack]) -> None:
    """Predict the mean and covariance of multiple object tracks using a shared Kalman filter."""
    BOTrack.multi_predict(tracks)

def reset(self) -> None:
    """Reset the BOTSORT tracker to its initial state, clearing all tracked objects and internal states."""
    super().reset()
    self.gmc.reset_params()

def __call__(self, img: np.ndarray, dets: np.ndarray) -> List[np.ndarray]:
    """Extract embeddings for detected objects."""
    feats = self.model.predictor(
        [save_one_box(det, img, save=False) for det in xywh2xyxy(torch.from_numpy(dets[:, :4]))]
    )
    if len(feats) != dets.shape[0] and feats[0].shape[0] == dets.shape[0]:
        feats = feats[0]  # batched prediction with non-PyTorch backend
    return [f.cpu().numpy() for f in feats]