import random import string from collections import defaultdict import numpy as np from scipy.spatial import distance as dist from frigate.config import DetectConfig from frigate.track import ObjectTracker from frigate.util import intersection_over_union class CentroidTracker(ObjectTracker): def __init__(self, config: DetectConfig): self.tracked_objects = {} self.untracked_object_boxes = [] self.disappeared = {} self.positions = {} self.max_disappeared = config.max_disappeared self.detect_config = config def register(self, index, obj): rand_id = "".join(random.choices(string.ascii_lowercase + string.digits, k=6)) id = f"{obj['frame_time']}-{rand_id}" obj["id"] = id obj["start_time"] = obj["frame_time"] obj["motionless_count"] = 0 obj["position_changes"] = 0 self.tracked_objects[id] = obj self.disappeared[id] = 0 self.positions[id] = { "xmins": [], "ymins": [], "xmaxs": [], "ymaxs": [], "xmin": 0, "ymin": 0, "xmax": self.detect_config.width, "ymax": self.detect_config.height, } def deregister(self, id): del self.tracked_objects[id] del self.disappeared[id] # tracks the current position of the object based on the last N bounding boxes # returns False if the object has moved outside its previous position def update_position(self, id, box): position = self.positions[id] position_box = ( position["xmin"], position["ymin"], position["xmax"], position["ymax"], ) xmin, ymin, xmax, ymax = box iou = intersection_over_union(position_box, box) # if the iou drops below the threshold # assume the object has moved to a new position and reset the computed box if iou < 0.6: self.positions[id] = { "xmins": [xmin], "ymins": [ymin], "xmaxs": [xmax], "ymaxs": [ymax], "xmin": xmin, "ymin": ymin, "xmax": xmax, "ymax": ymax, } return False # if there are less than 10 entries for the position, add the bounding box # and recompute the position box if len(position["xmins"]) < 10: position["xmins"].append(xmin) position["ymins"].append(ymin) position["xmaxs"].append(xmax) position["ymaxs"].append(ymax) # by using percentiles here, we hopefully remove outliers position["xmin"] = np.percentile(position["xmins"], 15) position["ymin"] = np.percentile(position["ymins"], 15) position["xmax"] = np.percentile(position["xmaxs"], 85) position["ymax"] = np.percentile(position["ymaxs"], 85) return True def is_expired(self, id): obj = self.tracked_objects[id] # get the max frames for this label type or the default max_frames = self.detect_config.stationary.max_frames.objects.get( obj["label"], self.detect_config.stationary.max_frames.default ) # if there is no max_frames for this label type, continue if max_frames is None: return False # if the object has exceeded the max_frames setting, deregister if ( obj["motionless_count"] - self.detect_config.stationary.threshold > max_frames ): return True return False def update(self, id, new_obj): self.disappeared[id] = 0 # update the motionless count if the object has not moved to a new position if self.update_position(id, new_obj["box"]): self.tracked_objects[id]["motionless_count"] += 1 if self.is_expired(id): self.deregister(id) return else: # register the first position change and then only increment if # the object was previously stationary if ( self.tracked_objects[id]["position_changes"] == 0 or self.tracked_objects[id]["motionless_count"] >= self.detect_config.stationary.threshold ): self.tracked_objects[id]["position_changes"] += 1 self.tracked_objects[id]["motionless_count"] = 0 self.tracked_objects[id].update(new_obj) def update_frame_times(self, frame_time): for id in list(self.tracked_objects.keys()): self.tracked_objects[id]["frame_time"] = frame_time self.tracked_objects[id]["motionless_count"] += 1 if self.is_expired(id): self.deregister(id) def match_and_update(self, frame_time, detections): # group by name detection_groups = defaultdict(lambda: []) for obj in detections: detection_groups[obj[0]].append( { "label": obj[0], "score": obj[1], "box": obj[2], "area": obj[3], "ratio": obj[4], "region": obj[5], "frame_time": frame_time, } ) # update any tracked objects with labels that are not # seen in the current objects and deregister if needed for obj in list(self.tracked_objects.values()): if obj["label"] not in detection_groups: if self.disappeared[obj["id"]] >= self.max_disappeared: self.deregister(obj["id"]) else: self.disappeared[obj["id"]] += 1 if len(detections) == 0: return # track objects for each label type for label, group in detection_groups.items(): current_objects = [ o for o in self.tracked_objects.values() if o["label"] == label ] current_ids = [o["id"] for o in current_objects] current_centroids = np.array([o["centroid"] for o in current_objects]) # compute centroids of new objects for obj in group: centroid_x = int((obj["box"][0] + obj["box"][2]) / 2.0) centroid_y = int((obj["box"][1] + obj["box"][3]) / 2.0) obj["centroid"] = (centroid_x, centroid_y) if len(current_objects) == 0: for index, obj in enumerate(group): self.register(index, obj) continue new_centroids = np.array([o["centroid"] for o in group]) # compute the distance between each pair of tracked # centroids and new centroids, respectively -- our # goal will be to match each current centroid to a new # object centroid D = dist.cdist(current_centroids, new_centroids) # in order to perform this matching we must (1) find the smallest # value in each row (i.e. the distance from each current object to # the closest new object) and then (2) sort the row indexes based # on their minimum values so that the row with the smallest # distance (the best match) is at the *front* of the index list rows = D.min(axis=1).argsort() # next, we determine which new object each existing object matched # against, and apply the same sorting as was applied previously cols = D.argmin(axis=1)[rows] # many current objects may register with each new object, so only # match the closest ones. unique returns the indices of the first # occurrences of each value, and because the rows are sorted by # distance, this will be index of the closest match _, index = np.unique(cols, return_index=True) rows = rows[index] cols = cols[index] # loop over the combination of the (row, column) index tuples for row, col in zip(rows, cols): # grab the object ID for the current row, set its new centroid, # and reset the disappeared counter objectID = current_ids[row] self.update(objectID, group[col]) # compute the row and column indices we have NOT yet examined unusedRows = set(range(D.shape[0])).difference(rows) unusedCols = set(range(D.shape[1])).difference(cols) # in the event that the number of object centroids is # equal or greater than the number of input centroids # we need to check and see if some of these objects have # potentially disappeared if D.shape[0] >= D.shape[1]: for row in unusedRows: id = current_ids[row] if self.disappeared[id] >= self.max_disappeared: self.deregister(id) else: self.disappeared[id] += 1 # if the number of input centroids is greater # than the number of existing object centroids we need to # register each new input centroid as a trackable object else: for col in unusedCols: self.register(col, group[col])