ultralytics 8.3.50 Enhanced segment resample (#18171)

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: UltralyticsAssistant <web@ultralytics.com>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>

ultralytics/__init__.py

@@ -1,6 +1,6 @@
 # Ultralytics YOLO 🚀, AGPL-3.0 license
 
-__version__ = "8.3.49"
+__version__ = "8.3.50"
 
 import os
 

ultralytics/data/dataset.py

@@ -218,8 +218,10 @@ class YOLODataset(BaseDataset):
         # NOTE: do NOT resample oriented boxes
         segment_resamples = 100 if self.use_obb else 1000
         if len(segments) > 0:
-            # list[np.array(1000, 2)] * num_samples
-            # (N, 1000, 2)
+            # make sure segments interpolate correctly if original length is greater than segment_resamples
+            max_len = max([len(s) for s in segments])
+            segment_resamples = (max_len + 1) if segment_resamples < max_len else segment_resamples
+            # list[np.array(segment_resamples, 2)] * num_samples
             segments = np.stack(resample_segments(segments, n=segment_resamples), axis=0)
         else:
             segments = np.zeros((0, segment_resamples, 2), dtype=np.float32)

ultralytics/utils/instance.py

@@ -7,7 +7,7 @@ from typing import List
 
 import numpy as np
 
-from .ops import ltwh2xywh, ltwh2xyxy, xywh2ltwh, xywh2xyxy, xyxy2ltwh, xyxy2xywh
+from .ops import ltwh2xywh, ltwh2xyxy, resample_segments, xywh2ltwh, xywh2xyxy, xyxy2ltwh, xyxy2xywh
 
 
 def _ntuple(n):
@@ -406,7 +406,20 @@ class Instances:
         normalized = instances_list[0].normalized
 
         cat_boxes = np.concatenate([ins.bboxes for ins in instances_list], axis=axis)
-        cat_segments = np.concatenate([b.segments for b in instances_list], axis=axis)
+        seg_len = [b.segments.shape[1] for b in instances_list]
+        if len(set(seg_len)) > 1:  # resample segments if there's different length
+            max_len = max(seg_len)
+            cat_segments = np.concatenate(
+                [
+                    resample_segments(list(b.segments), max_len)
+                    if len(b.segments)
+                    else np.zeros((0, max_len, 2), dtype=np.float32)  # re-generating empty segments
+                    for b in instances_list
+                ],
+                axis=axis,
+            )
+        else:
+            cat_segments = np.concatenate([b.segments for b in instances_list], axis=axis)
         cat_keypoints = np.concatenate([b.keypoints for b in instances_list], axis=axis) if use_keypoint else None
         return cls(cat_boxes, cat_segments, cat_keypoints, bbox_format, normalized)
 

ultralytics/utils/ops.py

@@ -624,6 +624,8 @@ def resample_segments(segments, n=1000):
         segments (list): the resampled segments.
     """
     for i, s in enumerate(segments):
+        if len(s) == n:
+            continue
         s = np.concatenate((s, s[0:1, :]), axis=0)
         x = np.linspace(0, len(s) - 1, n - len(s) if len(s) < n else n)
         xp = np.arange(len(s))