feat: implement Scene.to_json()

raillabel/format/metadata.py

@@ -55,3 +55,16 @@ def from_json(cls, json: JSONMetadata) -> Metadata:
                 setattr(metadata, extra_field, extra_value)
 
         return metadata
+
+    def to_json(self) -> JSONMetadata:
+        """Export this object into the RailLabel JSON format."""
+        return JSONMetadata(
+            schema_version=self.schema_version,
+            name=self.name,
+            subschema_version=self.subschema_version,
+            exporter_version=self.exporter_version,
+            file_version=self.file_version,
+            tagged_file=self.tagged_file,
+            annotator=self.annotator,
+            comment=self.comment,
+        )

raillabel/format/scene.py

@@ -11,13 +11,15 @@
     JSONFrame,
     JSONObject,
     JSONScene,
+    JSONSceneContent,
     JSONStreamCamera,
     JSONStreamOther,
     JSONStreamRadar,
 )
 
 from .camera import Camera
 from .frame import Frame
+from .frame_interval import FrameInterval
 from .gps_imu import GpsImu
 from .lidar import Lidar
 from .metadata import Metadata
@@ -52,6 +54,27 @@ def from_json(cls, json: JSONScene) -> Scene:
             frames=_frames_from_json(json.openlabel.frames),
         )
 
+    def to_json(self) -> JSONScene:
+        """Export this scene into the RailLabel JSON format."""
+        return JSONScene(
+            openlabel=JSONSceneContent(
+                metadata=self.metadata.to_json(),
+                streams={
+                    sensor_id: sensor.to_json()[0] for sensor_id, sensor in self.sensors.items()
+                },
+                coordinate_systems=_coordinate_systems_to_json(self.sensors),
+                objects={
+                    obj_id: obj.to_json(obj_id, self.frames) for obj_id, obj in self.objects.items()
+                },
+                frames={
+                    frame_id: frame.to_json(self.objects) for frame_id, frame in self.frames.items()
+                },
+                frame_intervals=[
+                    fi.to_json() for fi in FrameInterval.from_frame_ids(list(self.frames.keys()))
+                ],
+            )
+        )
+
 
 def _sensors_from_json(
     json_streams: dict[str, JSONStreamCamera | JSONStreamOther | JSONStreamRadar] | None,
@@ -95,3 +118,18 @@ def _frames_from_json(json_frames: dict[int, JSONFrame] | None) -> dict[int, Fra
         return {}
 
     return {frame_id: Frame.from_json(json_frame) for frame_id, json_frame in json_frames.items()}
+
+
+def _coordinate_systems_to_json(
+    sensors: dict[str, Camera | Lidar | Radar | GpsImu | OtherSensor],
+) -> dict[str, JSONCoordinateSystem]:
+    json_coordinate_systems = {
+        sensor_id: sensor.to_json()[1] for sensor_id, sensor in sensors.items()
+    }
+    json_coordinate_systems["base"] = JSONCoordinateSystem(
+        parent="",
+        type="local",
+        pose_wrt_parent=None,
+        children=list(json_coordinate_systems.keys()),
+    )
+    return json_coordinate_systems

tests/test_raillabel/format/test_metadata.py

@@ -61,5 +61,10 @@ def test_from_json__extra_fields():
     assert actual.ADDITIONAL_OBJECT == {"first_field": 2, "second_field": [1, 2, 3]}
 
 
+def test_to_json(metadata, metadata_json):
+    actual = metadata.to_json()
+    assert actual == metadata_json
+
+
 if __name__ == "__main__":
     pytest.main([__file__, "-v"])

tests/test_raillabel/format/test_object.py

@@ -83,6 +83,31 @@ def object_track_json() -> JSONObject:
     return JSONObject(
         name="track_0001",
         type="track",
+        frame_intervals=[JSONFrameInterval(frame_start=1, frame_end=1)],
+        object_data_pointers={
+            "rgb_middle__poly2d__track": JSONElementDataPointer(
+                frame_intervals=[JSONFrameInterval(frame_start=1, frame_end=1)],
+                type="poly2d",
+                attribute_pointers={
+                    "has_red_hat": "boolean",
+                    "has_green_hat": "boolean",
+                    "number_of_red_clothing_items": "num",
+                    "color_of_hat": "text",
+                    "clothing_items": "vec",
+                },
+            ),
+            "lidar__poly3d__track": JSONElementDataPointer(
+                frame_intervals=[JSONFrameInterval(frame_start=1, frame_end=1)],
+                type="poly3d",
+                attribute_pointers={
+                    "has_red_hat": "boolean",
+                    "has_green_hat": "boolean",
+                    "number_of_red_clothing_items": "num",
+                    "color_of_hat": "text",
+                    "clothing_items": "vec",
+                },
+            ),
+        },
     )
 
 
@@ -117,5 +142,10 @@ def test_to_json__person(object_person, object_person_json, object_person_id, fr
     assert actual == object_person_json
 
 
+def test_to_json__track(object_track, object_track_json, object_track_id, frame):
+    actual = object_track.to_json(object_track_id, {1: frame})
+    assert actual == object_track_json
+
+
 if __name__ == "__main__":
     pytest.main([__file__, "-vv"])

tests/test_raillabel/format/test_scene.py

@@ -6,7 +6,12 @@
 import pytest
 
 from raillabel.format import Scene
-from raillabel.json_format import JSONScene, JSONSceneContent, JSONCoordinateSystem
+from raillabel.json_format import (
+    JSONScene,
+    JSONSceneContent,
+    JSONCoordinateSystem,
+    JSONFrameInterval,
+)
 
 # == Fixtures =========================
 
@@ -47,6 +52,7 @@ def scene_json(
                 object_track_id: object_track_json,
             },
             frames={1: frame_json},
+            frame_intervals=[JSONFrameInterval(frame_start=1, frame_end=1)],
         )
     )
 
@@ -86,5 +92,10 @@ def test_from_json(scene, scene_json):
     assert actual == scene
 
 
+def test_to_json(scene, scene_json):
+    actual = scene.to_json()
+    assert actual == scene_json
+
+
 if __name__ == "__main__":
     pytest.main([__file__, "-v"])