This class represents the internel state of individual tracked objects observed as bbox.
| 59 | |
| 60 | |
| 61 | class KalmanBoxTracker(object): |
| 62 | """ |
| 63 | This class represents the internel state of individual tracked objects observed as bbox. |
| 64 | """ |
| 65 | count = 0 |
| 66 | |
| 67 | def __init__(self, bbox): |
| 68 | """ |
| 69 | Initialises a tracker using initial bounding box. |
| 70 | """ |
| 71 | # define constant velocity model |
| 72 | self.kf = KalmanFilter(dim_x=7, dim_z=4) |
| 73 | self.kf.F = np.array( |
| 74 | [[1, 0, 0, 0, 1, 0, 0], [0, 1, 0, 0, 0, 1, 0], [0, 0, 1, 0, 0, 0, 1], [0, 0, 0, 1, 0, 0, 0], |
| 75 | [0, 0, 0, 0, 1, 0, 0], [0, 0, 0, 0, 0, 1, 0], [0, 0, 0, 0, 0, 0, 1]]) |
| 76 | self.kf.H = np.array( |
| 77 | [[1, 0, 0, 0, 0, 0, 0], [0, 1, 0, 0, 0, 0, 0], [0, 0, 1, 0, 0, 0, 0], [0, 0, 0, 1, 0, 0, 0]]) |
| 78 | |
| 79 | self.kf.R[2:, 2:] *= 10. |
| 80 | self.kf.P[4:, 4:] *= 1000. # give high uncertainty to the unobservable initial velocities |
| 81 | self.kf.P *= 10. |
| 82 | self.kf.Q[-1, -1] *= 0.01 |
| 83 | self.kf.Q[4:, 4:] *= 0.01 |
| 84 | |
| 85 | self.kf.x[:4] = convert_bbox_to_z(bbox) |
| 86 | self.time_since_update = 0 |
| 87 | self.id = KalmanBoxTracker.count |
| 88 | KalmanBoxTracker.count += 1 |
| 89 | self.history = [] |
| 90 | self.hits = 0 |
| 91 | self.hit_streak = 0 |
| 92 | self.age = 0 |
| 93 | |
| 94 | def update(self, bbox): |
| 95 | """ |
| 96 | Updates the state vector with observed bbox. |
| 97 | """ |
| 98 | self.time_since_update = 0 |
| 99 | self.history = [] |
| 100 | self.hits += 1 |
| 101 | self.hit_streak += 1 |
| 102 | self.kf.update(convert_bbox_to_z(bbox)) |
| 103 | |
| 104 | def predict(self): |
| 105 | """ |
| 106 | Advances the state vector and returns the predicted bounding box estimate. |
| 107 | """ |
| 108 | if ((self.kf.x[6] + self.kf.x[2]) <= 0): |
| 109 | self.kf.x[6] *= 0.0 |
| 110 | self.kf.predict() |
| 111 | self.age += 1 |
| 112 | if (self.time_since_update > 0): |
| 113 | self.hit_streak = 0 |
| 114 | self.time_since_update += 1 |
| 115 | self.history.append(convert_x_to_bbox(self.kf.x)) |
| 116 | return self.history[-1] |
| 117 | |
| 118 | def get_state(self): |