[ghanashyam03]

Problem

sv.filter_polygons_by_area crashes with ValueError: zero-size array to reduction operation minimum which has no identity when any polygon in the input list has zero vertices (shape (0, 2)). This happens because _to_local_cv2_polygon calls polygon.min(axis=0) unconditionally without checking for empty polygons.
Similarly, sv.polygon_to_xyxy crashes with the same reduction ValueError when given an empty polygon instead of returning an all-zero bounding box matching Supervision's empty geometry convention (e.g. in mask_to_xyxy).

Root cause

• In _to_local_cv2_polygon, polygon.min(axis=0) lacks a guard for len(polygon) == 0. An empty polygon has area 0.0 in OpenCV (cv2.contourArea(np.empty((0, 2), dtype=np.float32)) == 0.0). Returning (np.empty((0, 2), dtype=np.float32), np.zeros(2, dtype=polygon.dtype)) allows cv2.contourArea to evaluate 0.0, so filter_polygons_by_area filters empty polygons cleanly according to min_area / max_area without crashing.
• In polygon_to_xyxy, calling np.min(polygon, axis=0) on a zero-size array raises ValueError. Checking len(polygon) == 0 and returning np.zeros(4, dtype=output_dtype) produces an all-zeros box while preserving caller dtype.

Change

• In src/supervision/detection/utils/polygons.py: added an empty-array check in _to_local_cv2_polygon to return (np.empty((0, 2), dtype=np.float32), np.zeros(2, dtype=polygon.dtype)) when len(polygon) == 0.
• In src/supervision/detection/utils/converters.py: added an empty-array check in polygon_to_xyxy to return np.zeros(4, dtype=output_dtype) when len(polygon) == 0.
• Added regression tests in tests/detection/utils/test_polygons.py and tests/detection/utils/test_converters.py covering empty polygons with area constraints and dtype preservation.

Regression coverage

• tests/detection/utils/test_polygons.py::test_filter_polygons_by_area: parameterized with empty polygon cases (min_area filter, max_area filter, and mixed empty + valid polygons).
• tests/detection/utils/test_converters.py::test_polygon_to_xyxy: parameterized with empty-polygon-int and empty-polygon-float32 verifying all-zeros bounding box output and dtype preservation.

Validation

• pytest tests/detection/utils/test_polygons.py tests/detection/utils/test_converters.py — 221 passed
• pytest tests/detection tests/geometry — 2378 passed, 1 skipped
• git diff --check — clean

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[ghanashyam03]

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Done

[Copilot]

🟡 Changes recommended

The user-visible fixes lack the changelog entry explicitly required by repository guidance.

1 open issue

• Add Unreleased changelog entry for empty polygon fixes · New

What changed in this PR

Fixes empty-polygon crashes in Supervision’s detection utilities.

Changes:

• Treats empty polygons as zero-area inputs when filtering.
• Returns zero bounding boxes with preserved NumPy dtype.
• Adds regression cases for filtering, mixed inputs, and dtype preservation.

Code: 5/5; tests: 4/5; documentation: 3/5. Risk: 1/5. Assessment covers behavior, regression coverage, and repository conventions; tests were not rerun.

File	Description
tests/​detection/​utils/​test_polygons.py	Tests empty and mixed polygons with area constraints.
tests/​detection/​utils/​test_converters.py	Tests empty inputs and bounding-box dtype preservation.
src/​supervision/​detection/​utils/​polygons.py	Guards empty polygons before coordinate reduction.
src/​supervision/​detection/​utils/​converters.py	Returns zero boxes for empty polygons and normalizes nonempty inputs.

_{Review effort: Balanced}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94%. Comparing base (cebbc5f) to head (7a00b73).

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #2761   +/-   ##
=======================================
  Coverage       94%     94%           
=======================================
  Files           83      83           
  Lines        13644   13650    +6     
=======================================
+ Hits         12841   12848    +7     
+ Misses         803     802    -1     

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