feat: Add YOLO_OBB format model

ref: https://docs.ultralytics.com/datasets/obb/#supported-obb-dataset-formats
ref: #280

label_studio_converter/converter.py

@@ -57,6 +57,7 @@ class Format(Enum):
     ASR_MANIFEST = 10
     YOLO = 11
     CSV_OLD = 12
+    YOLO_OBB = 13
 
     def __str__(self):
         return self.name
@@ -121,6 +122,14 @@ class Converter(object):
             'link': 'https://labelstud.io/guide/export.html#YOLO',
             'tags': ['image segmentation', 'object detection'],
         },
+        Format.YOLO_OBB: {
+            'title': 'YOLOv8-OBB',
+            'description': 'Popular TXT format is created for each image file. Each txt file contains annotations for '
+            'the corresponding image fileThe YOLO OBB format designates bounding boxes by their four corner points '
+            'with coordinates normalized between 0 and 1',
+            'link': 'https://labelstud.io/guide/export.html#YOLO',
+            'tags': ['image segmentation', 'object detection'],
+        },
         Format.BRUSH_TO_NUMPY: {
             'title': 'Brush labels to NumPy',
             'description': 'Export your brush labels as NumPy 2d arrays. Each label outputs as one image.',
@@ -215,7 +224,7 @@ def convert(self, input_data, output_data, format, is_dir=True, **kwargs):
             self.convert_to_coco(
                 input_data, output_data, output_image_dir=image_dir, is_dir=is_dir
             )
-        elif format == Format.YOLO:
+        elif format == Format.YOLO or format == Format.YOLO_OBB:
             image_dir = kwargs.get('image_dir')
             label_dir = kwargs.get('label_dir')
             self.convert_to_yolo(
@@ -224,6 +233,7 @@ def convert(self, input_data, output_data, format, is_dir=True, **kwargs):
                 output_image_dir=image_dir,
                 output_label_dir=label_dir,
                 is_dir=is_dir,
+                is_obb=(format == Format.YOLO_OBB)
             )
         elif format == Format.VOC:
             image_dir = kwargs.get('image_dir')
@@ -727,6 +737,7 @@ def convert_to_yolo(
         output_label_dir=None,
         is_dir=True,
         split_labelers=False,
+        is_obb=False,
     ):
         """Convert data in a specific format to the YOLO format.
 
@@ -744,8 +755,13 @@ def convert_to_yolo(
             A boolean indicating whether `input_data` is a directory (True) or a JSON file (False).
         split_labelers : bool, optional
             A boolean indicating whether to create a dedicated subfolder for each labeler in the output label directory.
+        is_obb : bool, optional
+            A boolean indicating whether the format is obb
         """
-        self._check_format(Format.YOLO)
+        if is_obb:
+            self._check_format(Format.YOLO_OBB)
+        else:
+            self._check_format(Format.YOLO)
         ensure_dir(output_dir)
         notes_file = os.path.join(output_dir, 'notes.json')
         class_file = os.path.join(output_dir, 'classes.txt')
@@ -851,20 +867,44 @@ def convert_to_yolo(
                         or 'rectangle' in label
                         or 'labels' in label
                     ):
-                        xywh = self.rotated_rectangle(label)
-                        if xywh is None:
-                            continue
+                        if is_obb:
+                            x1=label["x"]/100
+                            y1=label["y"]/100
+                            w=label["width"]/100
+                            h=label["height"]/100
+                            beta = math.pi * (
+                                label["rotation"] / 180
+                            ) if "rotation" in label else 0.0
+
+                            # Compute the vectors between points
+                            v12 = (h*math.sin(beta), h*math.cos(beta))
+                            v23 = (w * math.cos(beta), - w*math.sin(beta))
+
+                            annotations.append(
+                                [
+                                    category_id,
+                                    x1, y1,
+                                    x1 + v12[0], y1 + v12[1],
+                                    x1 + v12[0] + v23[0], y1 + v12[1] + v23[1],
+                                    x1 + v23[0], y1 + v23[1]
+                                ]
+                            )
 
-                        x, y, w, h = xywh
-                        annotations.append(
-                            [
-                                category_id,
-                                (x + w / 2) / 100,
-                                (y + h / 2) / 100,
-                                w / 100,
-                                h / 100,
-                            ]
-                        )
+                        else:
+                            xywh = self.rotated_rectangle(label)
+                            if xywh is None:
+                                continue
+
+                            x, y, w, h = xywh
+                            annotations.append(
+                                [
+                                    category_id,
+                                    (x + w / 2) / 100,
+                                    (y + h / 2) / 100,
+                                    w / 100,
+                                    h / 100,
+                                ]
+                            )
                     elif "polygonlabels" in label or 'polygon' in label:
                         points_abs = [(x / 100, y / 100) for x, y in label["points"]]
                         annotations.append(

label_studio_converter/main.py

@@ -151,6 +151,9 @@ def export(args):
         )
     elif args.format == Format.YOLO:
         c.convert_to_yolo(args.input, args.output, is_dir=not args.heartex_format)
+    elif args.format == Format.YOLO_OBB:
+        c.convert_to_yolo(args.input, args.output,
+                          is_dir=not args.heartex_format, is_obb=True)
     else:
         raise FormatNotSupportedError()
 

tests/test_export_yolo.py

@@ -54,6 +54,58 @@ def create_temp_folder():
     shutil.rmtree(temp_dir)
 
 
+def test_convert_to_yolo_obb(create_temp_folder):
+    """Check converstion label_studio json exported file to yolo with multiple labelers"""
+
+    # Generates a temporary folder and return the absolute path
+    # The temporary folder contains all the data generate by the following function
+    # For debugging replace create_temp_folder with "./tmp"
+    tmp_folder = create_temp_folder
+
+    output_dir = tmp_folder
+    output_image_dir = os.path.join(output_dir, "tmp_image")
+    output_label_dir = os.path.join(output_dir, "tmp_label")
+    project_dir = "."
+
+    converter = Converter(LABEL_CONFIG_PATH, project_dir)
+    converter.convert_to_yolo(
+        INPUT_JSON_PATH,
+        output_dir,
+        output_image_dir=output_image_dir,
+        output_label_dir=output_label_dir,
+        is_dir=False,
+        split_labelers=True,
+        is_obb=True,
+    )
+
+    abs_path_label_dir = os.path.abspath(output_label_dir)
+    expected_paths = [
+        os.path.join(abs_path_label_dir, "1", "image1.txt"),
+        os.path.join(abs_path_label_dir, "1", "image2.txt"),
+        os.path.join(abs_path_label_dir, "2", "image1.txt"),
+    ]
+    generated_paths = get_os_walk(abs_path_label_dir)
+    # Check all files and subfolders have been generated.
+    assert check_equal_list_of_strings(
+        expected_paths, generated_paths
+    ), f"Generated file: \n  {generated_paths} \n does not match expected ones: \n {expected_paths}"
+    # Check all the annotations have been converted to yolo
+    for file in expected_paths:
+        with open(file) as f:
+            lines = f.readlines()
+            for line in lines:
+                split_line = line.split(" ")
+                assert len(split_line) == 9, "OBB lines should have 9 parameters"
+                assert int(split_line[0]) == float(
+                    split_line[0]
+                ), f"Label should be an integer. Not {split_line[0]}"
+                for number in split_line:
+                    float(number)
+            assert (
+                len(lines) == 2
+            ), f"Expect different number of annotations in file {file}."
+
+
 def test_convert_to_yolo(create_temp_folder):
     """Check converstion label_studio json exported file to yolo with multiple labelers"""