Bounding boxes with rotation are not properly exported

[rgaiacs]

I created a single rotated bounding box annotation (image from https://commons.wikimedia.org/wiki/File:Radiography_of_a_pregnant_cat.jpg) with Label Studio:

and exported it COCO. When I try to visualise the bounding box, it differ from the one in Label Studio:

JSON

[
    {
        "id": 51406,
        "annotations": [
            {
                "id": 36030,
                "completed_by": 1,
                "result": [
                    {
                        "original_width": 1554,
                        "original_height": 2321,
                        "image_rotation": 0,
                        "value": {
                            "x": 47.87138334837448,
                            "y": 69.9849260797793,
                            "width": 11.016997871904488,
                            "height": 19.62824245339836,
                            "rotation": 296.74382057984246,
                            "rectanglelabels": [
                                "Bone"
                            ]
                        },
                        "id": "8jmhYeBOOD",
                        "from_name": "label",
                        "to_name": "image",
                        "type": "rectanglelabels",
                        "origin": "manual"
                    }
                ],
                "was_cancelled": false,
                "ground_truth": false,
                "created_at": "2022-10-13T05:04:58.401108Z",
                "updated_at": "2022-10-13T05:04:58.401155Z",
                "lead_time": 54.637,
                "prediction": {},
                "result_count": 0,
                "task": 51406,
                "parent_prediction": null,
                "parent_annotation": null
            }
        ],
        "file_upload": "39cd5e69-Radiography_of_a_pregnant_cat.jpeg",
        "drafts": [],
        "predictions": [],
        "data": {
            "image": "/data/upload/58/39cd5e69-Radiography_of_a_pregnant_cat.jpeg"
        },
        "meta": {},
        "created_at": "2022-10-13T05:04:01.311983Z",
        "updated_at": "2022-10-13T05:04:01.312017Z",
        "project": 58
    }
]

COCO

{
    "images": [
        {
            "width": 1554,
            "height": 2321,
            "id": 0,
            "file_name": "images/58/39cd5e69-Radiography_of_a_pregnant_cat.jpeg"
        }
    ],
    "categories": [
        {
            "id": 0,
            "name": "Bone"
        }
    ],
    "annotations": [
        {
            "id": 0,
            "image_id": 0,
            "category_id": 0,
            "segmentation": [],
            "bbox": [
                745,
                1614,
                171,
                455
            ],
            "ignore": 0,
            "iscrowd": 0,
            "area": 77805
        }
    ],
    "info": {
        "year": 2022,
        "version": "1.0",
        "description": "",
        "contributor": "Label Studio",
        "url": "",
        "date_created": "2022-10-13 06:15:42.968872"
    }
}

Solution

Change https://github.com/heartexlabs/label-studio-converter/blob/04124cd941feb633eac2fba01e0cbc89f6f5a367/label_studio_converter/converter.py#L526-L541 to take rotation into consideration.

[makseq]

Could you please check this PR: https://github.com/heartexlabs/label-studio-converter/pull/134 ?

[rgaiacs]

@makseq Thanks for the reply and the pull request. I tested the pull request and it didn't work.

The above figure illustrates the user case. User creates the red box and rotate it into the blue box. When exporting to COCO and YOLO, we want to export the green box.

[makseq]

@rgaiacs thank you for your great investigation and finalizing my PR!