Add option to use BBox tracking with SORT algorithm:

README.md

@@ -91,6 +91,11 @@ optional arguments:
                         This argument is expected in JSON notation. For a list
                         of possible options, refer to the ffmpeg-imageio docs.
                         Default: '{"codec": "libx264"}'.
+  --track-config        SORT arguments for bounding-box detection tracking, or 
+                        None if tracking should not be used.
+                        This argument is expected in JSON notation. For a list
+                        of possible options, refer to the original SORT repository.
+                        Default: None.
   --backend {auto,onnxrt,opencv}
                         Backend for ONNX model execution. Default: "auto"
                         (prefer onnxrt if available).

deface/deface.py

@@ -17,6 +17,7 @@
 
 from deface import __version__
 from deface.centerface import CenterFace
+from deface.sort import Sort
 
 
 # TODO: Optionally preserve audio track?
@@ -101,7 +102,8 @@ def video_detect(
         mask_scale: float,
         ellipse: bool,
         draw_scores: bool,
-        ffmpeg_config: Dict[str, str]
+        ffmpeg_config: Dict[str, str],
+        tracking_kwargs: Dict[str, float],
 ):
     try:
         reader: imageio.plugins.ffmpeg.FfmpegFormat.Reader = imageio.get_reader(ipath)
@@ -130,10 +132,17 @@ def video_detect(
             opath, format='FFMPEG', mode='I', fps=meta['fps'], **ffmpeg_config
         )
 
+    if tracking_kwargs is not None:
+        # use SORT BBox tracker from: https://github.com/abewley/sort
+        tracker = Sort(**tracking_kwargs)
+
     for frame in read_iter:
         # Perform network inference, get bb dets but discard landmark predictions
         dets, _ = centerface(frame, threshold=threshold)
 
+        if tracking_kwargs is not None:
+            dets = tracker.update(dets)
+
         anonymize_frame(
             dets, frame, mask_scale=mask_scale,
             replacewith=replacewith, ellipse=ellipse, draw_scores=draw_scores
@@ -232,6 +241,10 @@ def parse_cli_args():
         '--ffmpeg-config', default={"codec": "libx264"}, type=json.loads,
         help='FFMPEG config arguments for encoding output videos. This argument is expected in JSON notation. For a list of possible options, refer to the ffmpeg-imageio docs. Default: \'{"codec": "libx264"}\'.'
     )  # See https://imageio.readthedocs.io/en/stable/format_ffmpeg.html#parameters-for-saving
+    parser.add_argument(
+        '--track-config', default=None, type=json.loads,
+        help='SORT arguments for bounding-box detection tracking, or None if tracking should not be used. This argument is expected in JSON notation. For a list of possible options, refer to the original SORT repository. Default: None.'
+    )   # see https://github.com/abewley/sort/blob/master/sort.py#L199
     parser.add_argument(
         '--backend', default='auto', choices=['auto', 'onnxrt', 'opencv'],
         help='Backend for ONNX model execution. Default: "auto" (prefer onnxrt if available).')
@@ -268,6 +281,7 @@ def main():
     ffmpeg_config = args.ffmpeg_config
     backend = args.backend
     in_shape = args.scale
+    track_config = args.track_config
     if in_shape is not None:
         w, h = in_shape.split('x')
         in_shape = int(w), int(h)
@@ -306,7 +320,8 @@ def main():
                 draw_scores=draw_scores,
                 enable_preview=enable_preview,
                 nested=multi_file,
-                ffmpeg_config=ffmpeg_config
+                ffmpeg_config=ffmpeg_config,
+                tracking_kwargs=track_config
             )
         elif filetype == 'image':
             image_detect(

deface/sort.py

@@ -0,0 +1,245 @@
+"""
+    SORT: A Simple, Online and Realtime Tracker
+    Copyright (C) 2016-2020 Alex Bewley [email protected]
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+
+import numpy as np
+from filterpy.kalman import KalmanFilter
+
+
+def linear_assignment(cost_matrix):
+    try:
+        import lap
+        _, x, y = lap.lapjv(cost_matrix, extend_cost=True)
+        return np.array([[y[i], i] for i in x if i >= 0])  #
+    except ImportError:
+        from scipy.optimize import linear_sum_assignment
+        x, y = linear_sum_assignment(cost_matrix)
+        return np.array(list(zip(x, y)))
+
+
+def iou_batch(bb_test, bb_gt):
+    """
+    From SORT: Computes IOU between two bboxes in the form [x1,y1,x2,y2]
+    """
+    bb_gt = np.expand_dims(bb_gt, 0)
+    bb_test = np.expand_dims(bb_test, 1)
+
+    xx1 = np.maximum(bb_test[..., 0], bb_gt[..., 0])
+    yy1 = np.maximum(bb_test[..., 1], bb_gt[..., 1])
+    xx2 = np.minimum(bb_test[..., 2], bb_gt[..., 2])
+    yy2 = np.minimum(bb_test[..., 3], bb_gt[..., 3])
+    w = np.maximum(0., xx2 - xx1)
+    h = np.maximum(0., yy2 - yy1)
+    wh = w * h
+    o = wh / ((bb_test[..., 2] - bb_test[..., 0]) * (bb_test[..., 3] - bb_test[..., 1])
+              + (bb_gt[..., 2] - bb_gt[..., 0]) * (bb_gt[..., 3] - bb_gt[..., 1]) - wh)
+    return (o)
+
+
+def convert_bbox_to_z(bbox):
+    """
+    Takes a bounding box in the form [x1,y1,x2,y2] and returns z in the form
+      [x,y,s,r] where x,y is the centre of the box and s is the scale/area and r is
+      the aspect ratio
+    """
+    w = bbox[2] - bbox[0]
+    h = bbox[3] - bbox[1]
+    x = bbox[0] + w / 2.
+    y = bbox[1] + h / 2.
+    s = w * h  # scale is just area
+    r = w / float(h)
+    return np.array([x, y, s, r]).reshape((4, 1))
+
+
+def convert_x_to_bbox(x, score=None):
+    """
+    Takes a bounding box in the centre form [x,y,s,r] and returns it in the form
+      [x1,y1,x2,y2] where x1,y1 is the top left and x2,y2 is the bottom right
+    """
+    w = np.sqrt(x[2] * x[3])
+    h = x[2] / w
+    if (score == None):
+        return np.array([x[0] - w / 2., x[1] - h / 2., x[0] + w / 2., x[1] + h / 2.]).reshape(
+                (1, 4))
+    else:
+        return np.array(
+                [x[0] - w / 2., x[1] - h / 2., x[0] + w / 2., x[1] + h / 2., score]).reshape(
+                (1, 5))
+
+
+class KalmanBoxTracker(object):
+    """
+    This class represents the internal state of individual tracked objects observed as bbox.
+    """
+    count = 0
+
+    def __init__(self, bbox):
+        """
+        Initialises a tracker using initial bounding box.
+        """
+        # define constant velocity model
+        self.kf = KalmanFilter(dim_x=7, dim_z=4)
+        self.kf.F = np.array([[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], [0, 0, 0, 0, 1, 0, 0], [0, 0, 0, 0, 0, 1, 0],
+                              [0, 0, 0, 0, 0, 0, 1]])
+        self.kf.H = np.array([[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]])
+
+        self.kf.R[2:, 2:] *= 10.
+        self.kf.P[4:, 4:] *= 1000.  # give high uncertainty to the unobservable initial velocities
+        self.kf.P *= 10.
+        self.kf.Q[-1, -1] *= 0.01
+        self.kf.Q[4:, 4:] *= 0.01
+
+        self.kf.x[:4] = convert_bbox_to_z(bbox)
+        self.time_since_update = 0
+        self.id = KalmanBoxTracker.count
+        KalmanBoxTracker.count += 1
+        self.history = []
+        self.hits = 0
+        self.hit_streak = 0
+        self.age = 0
+
+    def update(self, bbox):
+        """
+        Updates the state vector with observed bbox.
+        """
+        self.time_since_update = 0
+        self.history = []
+        self.hits += 1
+        self.hit_streak += 1
+        self.kf.update(convert_bbox_to_z(bbox))
+
+    def predict(self):
+        """
+        Advances the state vector and returns the predicted bounding box estimate.
+        """
+        if ((self.kf.x[6] + self.kf.x[2]) <= 0):
+            self.kf.x[6] *= 0.0
+        self.kf.predict()
+        self.age += 1
+        if (self.time_since_update > 0):
+            self.hit_streak = 0
+        self.time_since_update += 1
+        self.history.append(convert_x_to_bbox(self.kf.x))
+        return self.history[-1]
+
+    def get_state(self):
+        """
+        Returns the current bounding box estimate.
+        """
+        return convert_x_to_bbox(self.kf.x)
+
+
+def associate_detections_to_trackers(detections, trackers, iou_threshold=0.3):
+    """
+    Assigns detections to tracked object (both represented as bounding boxes)
+    Returns 3 lists of matches, unmatched_detections and unmatched_trackers
+    """
+    if (len(trackers) == 0):
+        return np.empty((0, 2), dtype=int), np.arange(len(detections)), np.empty((0, 5), dtype=int)
+
+    iou_matrix = iou_batch(detections, trackers)
+
+    if min(iou_matrix.shape) > 0:
+        a = (iou_matrix > iou_threshold).astype(np.int32)
+        if a.sum(1).max() == 1 and a.sum(0).max() == 1:
+            matched_indices = np.stack(np.where(a), axis=1)
+        else:
+            matched_indices = linear_assignment(-iou_matrix)
+    else:
+        matched_indices = np.empty(shape=(0, 2))
+
+    unmatched_detections = []
+    for d, det in enumerate(detections):
+        if (d not in matched_indices[:, 0]):
+            unmatched_detections.append(d)
+    unmatched_trackers = []
+    for t, trk in enumerate(trackers):
+        if (t not in matched_indices[:, 1]):
+            unmatched_trackers.append(t)
+
+    # filter out matched with low IOU
+    matches = []
+    for m in matched_indices:
+        if (iou_matrix[m[0], m[1]] < iou_threshold):
+            unmatched_detections.append(m[0])
+            unmatched_trackers.append(m[1])
+        else:
+            matches.append(m.reshape(1, 2))
+    if (len(matches) == 0):
+        matches = np.empty((0, 2), dtype=int)
+    else:
+        matches = np.concatenate(matches, axis=0)
+
+    return matches, np.array(unmatched_detections), np.array(unmatched_trackers)
+
+
+class Sort(object):
+    def __init__(self, max_age=1, min_hits=3, iou_threshold=0.3):
+        """
+        Sets key parameters for SORT
+        """
+        self.max_age = max_age
+        self.min_hits = min_hits
+        self.iou_threshold = iou_threshold
+        self.trackers = []
+        self.frame_count = 0
+
+    def update(self, dets=np.empty((0, 5))):
+        """
+        Params:
+          dets - a numpy array of detections in the format [[x1,y1,x2,y2,score],[x1,y1,x2,y2,score],...]
+        Requires: this method must be called once for each frame even with empty detections (use np.empty((0, 5)) for frames without detections).
+        Returns the a similar array, where the last column is the object ID.
+        NOTE: The number of objects returned may differ from the number of detections provided.
+        """
+        self.frame_count += 1
+        # get predicted locations from existing trackers.
+        trks = np.zeros((len(self.trackers), 5))
+        to_del = []
+        ret = []
+        for t, trk in enumerate(trks):
+            pos = self.trackers[t].predict()[0]
+            trk[:] = [pos[0], pos[1], pos[2], pos[3], 0]
+            if np.any(np.isnan(pos)):
+                to_del.append(t)
+        trks = np.ma.compress_rows(np.ma.masked_invalid(trks))
+        for t in reversed(to_del):
+            self.trackers.pop(t)
+        matched, unmatched_dets, unmatched_trks = associate_detections_to_trackers(dets, trks,
+                                                                                   self.iou_threshold)
+
+        # update matched trackers with assigned detections
+        for m in matched:
+            self.trackers[m[1]].update(dets[m[0], :])
+
+        # create and initialise new trackers for unmatched detections
+        for i in unmatched_dets:
+            trk = KalmanBoxTracker(dets[i, :])
+            self.trackers.append(trk)
+        i = len(self.trackers)
+        for trk in reversed(self.trackers):
+            d = trk.get_state()[0]
+            if (trk.time_since_update < 1) and (
+                    trk.hit_streak >= self.min_hits or self.frame_count <= self.min_hits):
+                ret.append(np.concatenate((d, [trk.id + 1])).reshape(1,
+                                                                     -1))  # +1 as MOT benchmark requires positive
+            i -= 1
+            # remove dead tracklet
+            if (trk.time_since_update > self.max_age):
+                self.trackers.pop(i)
+        if (len(ret) > 0):
+            return np.concatenate(ret)
+        return np.empty((0, 5))

requirements.txt

@@ -3,4 +3,5 @@ imageio-ffmpeg
 numpy
 tqdm
 scikit-image
-opencv-python
+opencv-python
+filterpy

setup.py

@@ -27,6 +27,7 @@
         'tqdm',
         'scikit-image',
         'opencv-python',
+        'filterpy',
     ],
     extras_require={
         'gpu':  ['onnxruntime-gpu'],