import random import string import numpy as np from norfair import Detection, Drawable, Tracker, draw_boxes from norfair.drawing.drawer import Drawer from frigate.config import DetectConfig from frigate.track import ObjectTracker from frigate.util.image import intersection_over_union # Normalizes distance from estimate relative to object size # Other ideas: # - if estimates are inaccurate for first N detections, compare with last_detection (may be fine) # - could be variable based on time since last_detection # - include estimated velocity in the distance (car driving by of a parked car) # - include some visual similarity factor in the distance for occlusions def distance(detection: np.array, estimate: np.array) -> float: # ultimately, this should try and estimate distance in 3-dimensional space # consider change in location, width, and height estimate_dim = np.diff(estimate, axis=0).flatten() detection_dim = np.diff(detection, axis=0).flatten() # get bottom center positions detection_position = np.array( [np.average(detection[:, 0]), np.max(detection[:, 1])] ) estimate_position = np.array([np.average(estimate[:, 0]), np.max(estimate[:, 1])]) distance = (detection_position - estimate_position).astype(float) # change in x relative to w distance[0] /= estimate_dim[0] # change in y relative to h distance[1] /= estimate_dim[1] # get ratio of widths and heights # normalize to 1 widths = np.sort([estimate_dim[0], detection_dim[0]]) heights = np.sort([estimate_dim[1], detection_dim[1]]) width_ratio = widths[1] / widths[0] - 1.0 height_ratio = heights[1] / heights[0] - 1.0 # change vector is relative x,y change and w,h ratio change = np.append(distance, np.array([width_ratio, height_ratio])) # calculate euclidean distance of the change vector return np.linalg.norm(change) def frigate_distance(detection: Detection, tracked_object) -> float: return distance(detection.points, tracked_object.estimate) class NorfairTracker(ObjectTracker): def __init__(self, config: DetectConfig): self.tracked_objects = {} self.disappeared = {} self.positions = {} self.max_disappeared = config.max_disappeared self.detect_config = config self.track_id_map = {} # TODO: could also initialize a tracker per object class if there # was a good reason to have different distance calculations self.tracker = Tracker( distance_function=frigate_distance, distance_threshold=2.5, initialization_delay=0, hit_counter_max=self.max_disappeared, ) def register(self, track_id, obj): rand_id = "".join(random.choices(string.ascii_lowercase + string.digits, k=6)) id = f"{obj['frame_time']}-{rand_id}" self.track_id_map[track_id] = 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, track_id): del self.tracked_objects[id] del self.disappeared[id] self.tracker.tracked_objects = [ o for o in self.tracker.tracked_objects if o.global_id != track_id ] del self.track_id_map[track_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, track_id, obj): id = self.track_id_map[track_id] self.disappeared[id] = 0 # update the motionless count if the object has not moved to a new position if self.update_position(id, obj["box"]): self.tracked_objects[id]["motionless_count"] += 1 if self.is_expired(id): self.deregister(id, track_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(obj) def update_frame_times(self, frame_time): # if the object was there in the last frame, assume it's still there detections = [ ( obj["label"], obj["score"], obj["box"], obj["area"], obj["ratio"], obj["region"], ) for id, obj in self.tracked_objects.items() if self.disappeared[id] == 0 ] self.match_and_update(frame_time, detections=detections) def match_and_update(self, frame_time, detections): norfair_detections = [] for obj in detections: # centroid is used for other things downstream centroid_x = int((obj[2][0] + obj[2][2]) / 2.0) centroid_y = int((obj[2][1] + obj[2][3]) / 2.0) # track based on top,left and bottom,right corners instead of centroid points = np.array([[obj[2][0], obj[2][1]], [obj[2][2], obj[2][3]]]) norfair_detections.append( Detection( points=points, label=obj[0], data={ "label": obj[0], "score": obj[1], "box": obj[2], "area": obj[3], "ratio": obj[4], "region": obj[5], "frame_time": frame_time, "centroid": (centroid_x, centroid_y), }, ) ) tracked_objects = self.tracker.update(detections=norfair_detections) # update or create new tracks active_ids = [] for t in tracked_objects: estimate = tuple(t.estimate.flatten().astype(int)) # keep the estimate within the bounds of the image estimate = ( max(0, estimate[0]), max(0, estimate[1]), min(self.detect_config.width - 1, estimate[2]), min(self.detect_config.height - 1, estimate[3]), ) obj = { **t.last_detection.data, "estimate": estimate, } active_ids.append(t.global_id) if t.global_id not in self.track_id_map: self.register(t.global_id, obj) # if there wasn't a detection in this frame, increment disappeared elif t.last_detection.data["frame_time"] != frame_time: id = self.track_id_map[t.global_id] self.disappeared[id] += 1 # sometimes the estimate gets way off # only update if the upper left corner is actually upper left if estimate[0] < estimate[2] and estimate[1] < estimate[3]: self.tracked_objects[id]["estimate"] = obj["estimate"] # else update it else: self.update(t.global_id, obj) # clear expired tracks expired_ids = [k for k in self.track_id_map.keys() if k not in active_ids] for e_id in expired_ids: self.deregister(self.track_id_map[e_id], e_id) def debug_draw(self, frame, frame_time): active_detections = [ Drawable(id=obj.id, points=obj.last_detection.points, label=obj.label) for obj in self.tracker.tracked_objects if obj.last_detection.data["frame_time"] == frame_time ] missing_detections = [ Drawable(id=obj.id, points=obj.last_detection.points, label=obj.label) for obj in self.tracker.tracked_objects if obj.last_detection.data["frame_time"] != frame_time ] # draw the estimated bounding box draw_boxes(frame, self.tracker.tracked_objects, color="green", draw_ids=True) # draw the detections that were detected in the current frame draw_boxes(frame, active_detections, color="blue", draw_ids=True) # draw the detections that are missing in the current frame draw_boxes(frame, missing_detections, color="red", draw_ids=True) # draw the distance calculation for the last detection # estimate vs detection for obj in self.tracker.tracked_objects: ld = obj.last_detection # bottom right text_anchor = ( ld.points[1, 0], ld.points[1, 1], ) frame = Drawer.text( frame, f"{obj.id}: {str(obj.last_distance)}", position=text_anchor, size=None, color=(255, 0, 0), thickness=None, )