add camera_params and start validation

Author: Drew Kaul

nucleus/scene.py

@@ -1,6 +1,8 @@
 from dataclasses import dataclass
-from typing import Optional, Dict, List
+from typing import Optional, Dict, List, Set
 from enum import Enum
+from .annotation import Point3D
+from .utils import flatten
 
 
 class DatasetItemType(Enum):
@@ -9,12 +11,31 @@ class DatasetItemType(Enum):
     VIDEO = "video"
 
 
+@dataclass
+class Quaternion:
+    x: float
+    y: float
+    z: float
+    w: float
+
+
+@dataclass
+class CameraParams:
+    position: Point3D
+    heading: Quaternion
+    fx: float
+    fy: float
+    cx: float
+    cy: float
+
+
 @dataclass
 class SceneDatasetItem:
     url: str
     type: DatasetItemType
     reference_id: Optional[str] = None
     metadata: Optional[dict] = None
+    camera_params: Optional[CameraParams] = None
 
 
 @dataclass
@@ -40,4 +61,18 @@ class Scene:
 class LidarScene(Scene):
     def __post_init__(self):
         # do validation here for lidar scene
-        pass
+        lidar_sources = flatten(
+            [
+                [
+                    source
+                    for source in frame.items.keys()
+                    if frame.items[source].type == DatasetItemType.POINTCLOUD
+                ]
+                for frame in self.frames
+            ]
+        )
+        assert (
+            len(Set(lidar_sources)) == 1
+        ), "Each lidar scene must have exactly one lidar source"
+
+        # TODO: check single pointcloud per frame

nucleus/utils.py

@@ -32,6 +32,10 @@ def _get_all_field_values(metadata_list: List[dict], key: str):
     return {metadata[key] for metadata in metadata_list if key in metadata}
 
 
+def flatten(t):
+    return [item for sublist in t for item in sublist]
+
+
 def suggest_metadata_schema(
     data: Union[
         List[DatasetItem], List[BoxPrediction], List[PolygonPrediction]