add comment about landsat bands

rslp/landsat_vessels/predict_pipeline.py

@@ -420,7 +420,12 @@ def predict_pipeline(
         if near_infra_filter.should_filter(lon, lat):
             infra_detections += 1
             continue
-        # Load crops from the window directory.
+
+        # Load crops from the window directory for writing output PNGs.
+        # We create two PNGs:
+        # - b8.png: just has B8 (panchromatic band).
+        # - rgb.png: true color with pan-sharpening. The RGB is from B4, B3, and B2
+        #   respectively while B8 is used for pan-sharpening.
         images = {}
         crop_window_dir = detection.metadata["crop_window_dir"]
         if crop_window_dir is None:

rslp/vessels/__init__.py

@@ -22,7 +22,7 @@ def __init__(
         ts: datetime | None = None,
         scene_id: str | None = None,
         crop_fname: UPath | None = None,
-        metadata: dict[str, Any] = {},
+        metadata: dict[str, Any] | None = None,
     ) -> None:
         """Create a new VesselDetection.
 
@@ -45,7 +45,11 @@ def __init__(
         self.ts = ts
         self.scene_id = scene_id
         self.crop_fname = crop_fname
-        self.metadata = metadata
+
+        if metadata is None:
+            self.metadata = {}
+        else:
+            self.metadata = metadata
 
     def get_lon_lat(self) -> tuple[float, float]:
         """Get the longitude and latitude of this detection.