import copy import datetime import itertools import multiprocessing as mp import random import string import threading import time from collections import defaultdict import cv2 import numpy as np from scipy.spatial import distance as dist from frigate.config import DetectConfig from frigate.util import intersection_over_union class ObjectTracker: def __init__(self, config: DetectConfig): self.tracked_objects = {} 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 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 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 self.tracked_objects.keys(): self.tracked_objects[id]["frame_time"] = frame_time self.tracked_objects[id]["motionless_count"] += 1 def match_and_update(self, frame_time, new_objects): # group by name new_object_groups = defaultdict(lambda: []) for obj in new_objects: new_object_groups[obj[0]].append( { "label": obj[0], "score": obj[1], "box": obj[2], "area": obj[3], "region": obj[4], "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 not obj["label"] in new_object_groups: if self.disappeared[obj["id"]] >= self.max_disappeared: self.deregister(obj["id"]) else: self.disappeared[obj["id"]] += 1 if len(new_objects) == 0: return # track objects for each label type for label, group in new_object_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])