roboflow/supervision · error · ValueError

corners must have shape (N, 4, 2); got {c.shape}

Error message

corners must have shape (N, 4, 2); got {c.shape}

What it means

Error "corners must have shape (N, 4, 2); got {c.shape}" thrown in roboflow/supervision.

Source

Thrown at src/supervision/detection/core.py:3318

        if total_area > 0:
            confidence = np.array(
                [float(np.dot(areas, confidences) / total_area)],
                dtype=np.float32,
            )
        else:
            confidence = winner.confidence
    else:
        confidence = None

    # OBB path: merge corners via winner-angle projection, then derive xyxy
    # from the merged OBB so both stay consistent.
    has_obb = ORIENTED_BOX_COORDINATES in winner.data
    if has_obb:
        corners_list = []
        for det in detections:
            c = np.asarray(det.data[ORIENTED_BOX_COORDINATES])
            if c.ndim != 3 or c.shape[1:] != (4, 2):
                raise ValueError(f"corners must have shape (N, 4, 2); got {c.shape}")
            corners_list.append(c[0].reshape(4, 2))
        merged_corners = _merge_obb_corners(corners_list)
        xyxy = xyxyxyxy_to_xyxy(merged_corners[np.newaxis])
        data = {**winner.data, ORIENTED_BOX_COORDINATES: merged_corners[np.newaxis]}
    else:
        # AABB path: union bounding box across all group members
        xyxy = np.array(
            [
                [
                    all_xyxy[:, 0].min(),
                    all_xyxy[:, 1].min(),
                    all_xyxy[:, 2].max(),
                    all_xyxy[:, 3].max(),
                ]
            ],
            dtype=np.float32,
        )
        data = winner.data

View on GitHub (pinned to 7f254d9784)

Solutions

1. Pass corners as an array of shape (N, 4, 2): N boxes, each with 4 corner points of (x, y) coordinates.
2. If you have a flat (N, 8) array, reshape it with corners.reshape(-1, 4, 2) before calling.

When it happens

Trigger: Thrown at src/supervision/detection/core.py:3318 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of roboflow/supervision@7f254d9784 (2026-08-15). Data as JSON: /api/errors/73aaed5cec11b7c9. Report an issue: GitHub.