feat(raw frame unit): adapting dataset reader so that raw depth frames are scaled according to the requested unit

src/lerobot/datasets/dataset_reader.py

@@ -22,10 +22,14 @@ from pathlib import Path
 import datasets
 import torch
 
-from lerobot.configs import DEFAULT_DEPTH_UNIT, DepthEncoderConfig
+from lerobot.configs import (
+    DEFAULT_DEPTH_UNIT,
+    DEPTH_METER_UNIT,
+    DepthEncoderConfig,
+)
 
 from .dataset_metadata import LeRobotDatasetMetadata
-from .depth_utils import dequantize_depth
+from .depth_utils import MM_PER_METRE, dequantize_depth
 from .feature_utils import (
     check_delta_timestamps,
     get_delta_indices,
@@ -102,6 +106,13 @@ class DatasetReader:
             for vid_key in self._meta.depth_keys
         }
 
+        # Get the input unit of each depth feature stored as raw images.
+        self._image_depth_units: dict[str, str | None] = {
+            key: (self._meta.features[key].get("info") or {}).get("depth_unit")
+            for key in self._meta.depth_keys
+            if key in self._meta.image_keys
+        }
+
     def set_image_transforms(self, image_transforms: Callable | None) -> None:
         """Replace the transform applied to visual observations."""
         if image_transforms is not None and not callable(image_transforms):
@@ -329,6 +340,13 @@ class DatasetReader:
                     continue
                 item[cam] = self._image_transforms(item[cam])
 
+        # Convert depth features to the output unit.
+        for key, stored_unit in self._image_depth_units.items():
+            if key in item and stored_unit is not None and stored_unit != self._depth_output_unit:
+                item[key] = (
+                    item[key] * MM_PER_METRE if stored_unit == DEPTH_METER_UNIT else item[key] / MM_PER_METRE
+                )
+
         # Add task as a string
         task_idx = item["task_index"].item()
         item["task"] = self._meta.tasks.iloc[task_idx].name