add feature: max tracking id threshold

README.md

@@ -66,6 +66,15 @@ To display the results you need to:
   $ python sort.py --display
   ```
 
+Added command-line argument --max_id_threshold
+
+```bash
+# Unlimited IDs (default behavior)
+python sort.py 
+
+# Limited to 1000 IDs
+python sort.py --max_id_threshold 1000
+```
 
 ### Main Results
 

sort.py

@@ -20,7 +20,7 @@
 import os
 import numpy as np
 import matplotlib
-matplotlib.use('TkAgg')
+matplotlib.use('Agg')
 import matplotlib.pyplot as plt
 import matplotlib.patches as patches
 from skimage import io
@@ -104,7 +104,7 @@ def __init__(self,bbox):
     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.
@@ -197,15 +197,60 @@ def associate_detections_to_trackers(detections,trackers,iou_threshold = 0.3):
 
 
 class Sort(object):
-  def __init__(self, max_age=1, min_hits=3, iou_threshold=0.3):
+  def __init__(self, max_age=1, min_hits=3, iou_threshold=0.3, max_id_threshold=None):
     """
     Sets key parameters for SORT
     """
     self.max_age = max_age
     self.min_hits = min_hits
     self.iou_threshold = iou_threshold
+    self.max_id_threshold = max_id_threshold  # None means unlimited IDs
     self.trackers = []
     self.frame_count = 0
+    # Add ID management for keeping track of currently active IDs
+    self.active_ids = set()
+    self.next_available_id = 1
+
+  def get_next_id(self):
+    """
+    Get the next available ID, respecting the max_id_threshold if set
+    """
+    if self.max_id_threshold is None:
+      # Unlimited IDs - just increment and reuse released IDs when possible
+      while self.next_available_id in self.active_ids:
+        self.next_available_id += 1
+
+      current_id = self.next_available_id
+      self.active_ids.add(current_id)
+      self.next_available_id += 1
+      return current_id
+    else:
+      # Limited IDs - respect the maximum id threshold
+      # Find the next available ID that isn't currently active
+      while self.next_available_id in self.active_ids and self.next_available_id <= self.max_id_threshold:
+        self.next_available_id += 1
+
+      if self.next_available_id > self.max_id_threshold:
+        # If we've exceeded threshold, find the first available ID from 1 to threshold
+        for i in range(1, self.max_id_threshold + 1):
+          if i not in self.active_ids:
+            self.next_available_id = i
+            break
+        else:
+          # If all IDs 1-threshold are active (rare case), wrap around
+          self.next_available_id = 1
+
+      current_id = self.next_available_id
+      self.active_ids.add(current_id)
+      self.next_available_id += 1
+      return current_id
+
+  def release_id(self, tracker_id):
+    """
+    Remove an ID from active set when tracker is deleted
+    """
+    if tracker_id in self.active_ids:
+      self.active_ids.remove(tracker_id)
 
   def update(self, dets=np.empty((0, 5))):
     """
@@ -239,14 +284,22 @@ def update(self, dets=np.empty((0, 5))):
     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
+          # Use managed ID system instead of the original logic
+          if not hasattr(trk, 'assigned_id'):
+            trk.assigned_id = self.get_next_id()
+
+          ret.append(np.concatenate((d,[trk.assigned_id])).reshape(1,-1))
         i -= 1
         # remove dead tracklet
         if(trk.time_since_update > self.max_age):
+          # Release the ID when removing the tracker
+          if hasattr(trk, 'assigned_id'):
+            self.release_id(trk.assigned_id)
           self.trackers.pop(i)
     if(len(ret)>0):
       return np.concatenate(ret)
@@ -265,6 +318,9 @@ def parse_args():
                         help="Minimum number of associated detections before track is initialised.", 
                         type=int, default=3)
     parser.add_argument("--iou_threshold", help="Minimum IOU for match.", type=float, default=0.3)
+    parser.add_argument("--max_id_threshold", 
+                        help="Maximum tracking ID threshold. If not specified, IDs can grow indefinitely.", 
+                        type=int, default=None)
     args = parser.parse_args()
     return args
 
@@ -290,7 +346,8 @@ def parse_args():
   for seq_dets_fn in glob.glob(pattern):
     mot_tracker = Sort(max_age=args.max_age, 
                        min_hits=args.min_hits,
-                       iou_threshold=args.iou_threshold) #create instance of the SORT tracker
+                       iou_threshold=args.iou_threshold,
+                       max_id_threshold=args.max_id_threshold) #create instance of the SORT tracker
     seq_dets = np.loadtxt(seq_dets_fn, delimiter=',')
     seq = seq_dets_fn[pattern.find('*'):].split(os.path.sep)[0]
 
@@ -327,4 +384,4 @@ def parse_args():
   print("Total Tracking took: %.3f seconds for %d frames or %.1f FPS" % (total_time, total_frames, total_frames / total_time))
 
   if(display):
-    print("Note: to get real runtime results run without the option: --display")
+    print("Note: to get real runtime results run without the option: --display")