From 5a546a49abce7d8101a89dbf71bb5353072f0876 Mon Sep 17 00:00:00 2001
From: Kentaro Wada <www.kentaro.wada@gmail.com>
Date: Sat, 6 Jan 2024 22:31:23 +0900
Subject: [PATCH] Handle empty contour case

---
 labelme/ai/_utils.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/labelme/ai/_utils.py b/labelme/ai/_utils.py
index 2619ac137..6806a5b06 100644
--- a/labelme/ai/_utils.py
+++ b/labelme/ai/_utils.py
@@ -2,6 +2,8 @@
 import numpy as np
 import skimage
 
+from labelme.logger import logger
+
 
 def _get_contour_length(contour):
     contour_start = contour
@@ -11,6 +13,10 @@ def _get_contour_length(contour):
 
 def compute_polygon_from_mask(mask):
     contours = skimage.measure.find_contours(np.pad(mask, pad_width=1))
+    if len(contours) == 0:
+        logger.warning("No contour found, so returning empty polygon.")
+        return np.empty((0, 2), dtype=np.float32)
+
     contour = max(contours, key=_get_contour_length)
     POLYGON_APPROX_TOLERANCE = 0.004
     polygon = skimage.measure.approximate_polygon(