Merge pull request #1493 from mikel-brostrom/xyah-xywh-kf-refactor

bytetrack, strongsort and botsort kf refactor

boxmot/motion/cmc/cmc_interface.py → boxmot/motion/cmc/base_cmc.py

@@ -5,7 +5,7 @@
 from abc import ABC, abstractmethod
 
 
-class CMCInterface(ABC):
+class BaseCMC(ABC):
 
     @abstractmethod
     def apply(self, im):

boxmot/motion/cmc/ecc.py

@@ -5,12 +5,12 @@
 import cv2
 import numpy as np
 
-from boxmot.motion.cmc.cmc_interface import CMCInterface
+from boxmot.motion.cmc.base_cmc import BaseCMC
 from boxmot.utils import BOXMOT
 from boxmot.utils import logger as LOGGER
 
 
-class ECC(CMCInterface):
+class ECC(BaseCMC):
     def __init__(
         self,
         warp_mode: int = cv2.MOTION_EUCLIDEAN,

boxmot/motion/cmc/orb.py

@@ -6,11 +6,11 @@
 import cv2
 import numpy as np
 
-from boxmot.motion.cmc.cmc_interface import CMCInterface
+from boxmot.motion.cmc.base_cmc import BaseCMC
 from boxmot.utils import BOXMOT
 
 
-class ORB(CMCInterface):
+class ORB(BaseCMC):
 
     def __init__(
         self,

boxmot/motion/cmc/sift.py

@@ -6,11 +6,11 @@
 import cv2
 import numpy as np
 
-from boxmot.motion.cmc.cmc_interface import CMCInterface
+from boxmot.motion.cmc.base_cmc import BaseCMC
 from boxmot.utils import BOXMOT
 
 
-class SIFT(CMCInterface):
+class SIFT(BaseCMC):
 
     def __init__(
         self,

boxmot/motion/cmc/sof.py

@@ -5,12 +5,12 @@
 import cv2
 import numpy as np
 
-from boxmot.motion.cmc.cmc_interface import CMCInterface
+from boxmot.motion.cmc.base_cmc import BaseCMC
 from boxmot.utils import BOXMOT
 from boxmot.utils import logger as LOGGER
 
 
-class SOF(CMCInterface):
+class SOF(BaseCMC):
 
     def __init__(
         self,

boxmot/motion/kalman_filters/base_kalman_filter.py

@@ -0,0 +1,158 @@
+import numpy as np
+import scipy.linalg
+from typing import Tuple
+
+"""
+Table for the 0.95 quantile of the chi-square distribution with N degrees of
+freedom (contains values for N=1, ..., 9). Taken from MATLAB/Octave's chi2inv
+function and used as Mahalanobis gating threshold.
+"""
+chi2inv95 = {
+    1: 3.8415,
+    2: 5.9915,
+    3: 7.8147,
+    4: 9.4877,
+    5: 11.070,
+    6: 12.592,
+    7: 14.067,
+    8: 15.507,
+    9: 16.919
+}
+
+class BaseKalmanFilter:
+    """
+    Base class for Kalman filters tracking bounding boxes in image space.
+    """
+
+    def __init__(self, ndim: int):
+        self.ndim = ndim
+        self.dt = 1.
+
+        # Create Kalman filter model matrices.
+        self._motion_mat = np.eye(2 * ndim, 2 * ndim)  # State transition matrix
+        for i in range(ndim):
+            self._motion_mat[i, ndim + i] = self.dt
+        self._update_mat = np.eye(ndim, 2 * ndim)  # Observation matrix
+
+        # Motion and observation uncertainty weights.
+        self._std_weight_position = 1. / 20
+        self._std_weight_velocity = 1. / 160
+
+    def initiate(self, measurement: np.ndarray) -> Tuple[np.ndarray, np.ndarray]:
+        """
+        Create track from unassociated measurement.
+        """
+        mean_pos = measurement
+        mean_vel = np.zeros_like(mean_pos)
+        mean = np.r_[mean_pos, mean_vel]
+
+        std = self._get_initial_covariance_std(measurement)
+        covariance = np.diag(np.square(std))
+        return mean, covariance
+
+    def _get_initial_covariance_std(self, measurement: np.ndarray) -> np.ndarray:
+        """
+        Return initial standard deviations for the covariance matrix.
+        Should be implemented by subclasses.
+        """
+        raise NotImplementedError
+
+    def predict(self, mean: np.ndarray, covariance: np.ndarray) -> Tuple[np.ndarray, np.ndarray]:
+        """
+        Run Kalman filter prediction step.
+        """
+        std_pos, std_vel = self._get_process_noise_std(mean)
+        motion_cov = np.diag(np.square(np.r_[std_pos, std_vel]))
+
+        mean = np.dot(mean, self._motion_mat.T)
+        covariance = np.linalg.multi_dot((
+            self._motion_mat, covariance, self._motion_mat.T)) + motion_cov
+
+        return mean, covariance
+
+    def _get_process_noise_std(self, mean: np.ndarray) -> Tuple[np.ndarray, np.ndarray]:
+        """
+        Return standard deviations for process noise.
+        Should be implemented by subclasses.
+        """
+        raise NotImplementedError
+
+    def project(self, mean: np.ndarray, covariance: np.ndarray, confidence: float = 0.0) -> Tuple[np.ndarray, np.ndarray]:
+        """
+        Project state distribution to measurement space.
+        """
+        std = self._get_measurement_noise_std(mean, confidence)
+
+        # NSA Kalman algorithm from GIAOTracker, which proposes a formula to 
+        # adaptively calculate the noise covariance Rek:
+        # Rk = (1 − ck) Rk
+        # where Rk is the preset constant measurement noise covariance
+        # and ck is the detection confidence score at state k. Intuitively,
+        # the detection has a higher score ck when it has less noise,
+        # which results in a low Re.
+        std = [(1 - confidence) * x for x in std]
+
+        innovation_cov = np.diag(np.square(std))
+
+        mean = np.dot(self._update_mat, mean)
+        covariance = np.linalg.multi_dot((
+            self._update_mat, covariance, self._update_mat.T))
+        return mean, covariance + innovation_cov
+
+    def multi_predict(self, mean: np.ndarray, covariance: np.ndarray) -> Tuple[np.ndarray, np.ndarray]:
+        """
+        Run Kalman filter prediction step (Vectorized version).
+        """
+        std_pos, std_vel = self._get_multi_process_noise_std(mean)
+        sqr = np.square(np.r_[std_pos, std_vel]).T
+
+        motion_cov = [np.diag(sqr[i]) for i in range(len(mean))]
+        motion_cov = np.asarray(motion_cov)
+
+        mean = np.dot(mean, self._motion_mat.T)
+        left = np.dot(self._motion_mat, covariance).transpose((1, 0, 2))
+        covariance = np.dot(left, self._motion_mat.T) + motion_cov
+
+        return mean, covariance
+
+    def update(self, mean: np.ndarray, covariance: np.ndarray, measurement: np.ndarray, confidence: float = 0.0) -> Tuple[np.ndarray, np.ndarray]:
+        """
+        Run Kalman filter correction step.
+        """
+        projected_mean, projected_cov = self.project(mean, covariance, confidence)
+
+        chol_factor, lower = scipy.linalg.cho_factor(projected_cov, lower=True, check_finite=False)
+        kalman_gain = scipy.linalg.cho_solve((chol_factor, lower), np.dot(covariance, self._update_mat.T).T, check_finite=False).T
+        innovation = measurement - projected_mean
+
+        new_mean = mean + np.dot(innovation, kalman_gain.T)
+        new_covariance = covariance - np.linalg.multi_dot((kalman_gain, projected_cov, kalman_gain.T))
+        return new_mean, new_covariance
+
+    def _get_multi_process_noise_std(self, mean: np.ndarray) -> Tuple[np.ndarray, np.ndarray]:
+        """
+        Return standard deviations for process noise in vectorized form.
+        Should be implemented by subclasses.
+        """
+        raise NotImplementedError
+
+    def gating_distance(self, mean: np.ndarray, covariance: np.ndarray, measurements: np.ndarray, only_position: bool = False, metric: str = 'maha') -> np.ndarray:
+        """
+        Compute gating distance between state distribution and measurements.
+        """
+        mean, covariance = self.project(mean, covariance)
+
+        if only_position:
+            mean, covariance = mean[:2], covariance[:2, :2]
+            measurements = measurements[:, :2]
+
+        d = measurements - mean
+        if metric == 'gaussian':
+            return np.sum(d * d, axis=1)
+        elif metric == 'maha':
+            cholesky_factor = np.linalg.cholesky(covariance)
+            z = scipy.linalg.solve_triangular(cholesky_factor, d.T, lower=True, check_finite=False, overwrite_b=True)
+            squared_maha = np.sum(z * z, axis=0)
+            return squared_maha
+        else:
+            raise ValueError('invalid distance metric')