BeninSmallHolderCashews: return geospatial metadata in sample (#377)

* exposing geoinformation

* restoring white spaces

* Returns tile_transform and crs
instead of storing it in self.
Adapt docstring

* adding types

* adjust line length

* fixing formatting

* remove auto-format from another auto-pep8 tool

* adjust order of import

* radjust autopep8

* passes pre-commit hook

* Add Oxford comma

* tile_transform -> transform

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

torchgeo/datasets/benin_cashews.py

@@ -13,6 +13,7 @@
 import rasterio
 import rasterio.features
 import torch
+from rasterio.crs import CRS
 from torch import Tensor
 
 from .geo import VisionDataset
@@ -233,12 +234,12 @@ def __getitem__(self, index: int) -> Dict[str, Tensor]:
             index: index to return
 
         Returns:
-            image, mask, and metadata at that index
+            a dict containing image, mask, transform, crs, and metadata at index.
         """
         y, x = self.chips_metadata[index]
 
-        img = self._load_all_imagery(self.bands)
-        labels = self._load_mask()
+        img, transform, crs = self._load_all_imagery(self.bands)
+        labels = self._load_mask(transform)
 
         img = img[:, :, y : y + self.chip_size, x : x + self.chip_size]
         labels = labels[y : y + self.chip_size, x : x + self.chip_size]
@@ -248,6 +249,8 @@ def __getitem__(self, index: int) -> Dict[str, Tensor]:
             "mask": labels,
             "x": torch.tensor(x),  # type: ignore[attr-defined]
             "y": torch.tensor(y),  # type: ignore[attr-defined]
+            "transform": transform,
+            "crs": crs,
         }
 
         if self.transforms is not None:
@@ -279,17 +282,21 @@ def _validate_bands(self, bands: Tuple[str, ...]) -> None:
                 raise ValueError(f"'{band}' is an invalid band name.")
 
     @lru_cache(maxsize=128)
-    def _load_all_imagery(self, bands: Tuple[str, ...] = ALL_BANDS) -> Tensor:
+    def _load_all_imagery(
+        self, bands: Tuple[str, ...] = ALL_BANDS
+    ) -> Tuple[Tensor, rasterio.Affine, CRS]:
         """Load all the imagery (across time) for the dataset.
 
         Optionally allows for subsetting of the bands that are loaded.
 
         Args:
             bands: tuple of bands to load
 
-        Returns
-            imagery of shape (70, number of bands, 1186, 1122) where 70 is the number of
-                points in time, 1186 is the tile height, and 1122 is the tile width
+        Returns:
+            imagery of shape (70, number of bands, 1186, 1122) where 70 is the number
+            of points in time, 1186 is the tile height, and 1122 is the tile width
+            rasterio affine transform, mapping pixel coordinates to geo coordinates
+            coordinate reference system of transform
         """
         if self.verbose:
             print("Loading all imagery")
@@ -303,12 +310,15 @@ def _load_all_imagery(self, bands: Tuple[str, ...] = ALL_BANDS) -> Tensor:
         )
 
         for date_index, date in enumerate(self.dates):
-            img[date_index] = self._load_single_scene(date, self.bands)
+            single_scene, transform, crs = self._load_single_scene(date, self.bands)
+            img[date_index] = single_scene
 
-        return img
+        return img, transform, crs
 
     @lru_cache(maxsize=128)
-    def _load_single_scene(self, date: str, bands: Tuple[str, ...]) -> Tensor:
+    def _load_single_scene(
+        self, date: str, bands: Tuple[str, ...]
+    ) -> Tuple[Tensor, rasterio.Affine, CRS]:
         """Load the imagery for a single date.
 
         Optionally allows for subsetting of the bands that are loaded.
@@ -318,7 +328,9 @@ def _load_single_scene(self, date: str, bands: Tuple[str, ...]) -> Tensor:
             bands: bands to load
 
         Returns:
-            tensor containing a single image tile
+            Tensor containing a single image tile, rasterio affine transform,
+            mapping pixel coordinates to geo coordinates, and coordinate
+            reference system of transform.
 
         Raises:
             AssertionError: if  ``date`` is invalid
@@ -342,14 +354,15 @@ def _load_single_scene(self, date: str, bands: Tuple[str, ...]) -> Tensor:
                 f"{band_name}.tif",
             )
             with rasterio.open(filepath) as src:
-                self.tile_transform = src.transform
+                transform = src.transform  # same transform for every bands
+                crs = src.crs
                 array = src.read().astype(np.float32)
                 img[band_index] = torch.from_numpy(array)  # type: ignore[attr-defined]
 
-        return img
+        return img, transform, crs
 
     @lru_cache()
-    def _load_mask(self) -> Tensor:
+    def _load_mask(self, transform: rasterio.Affine) -> Tensor:
         """Rasterizes the dataset's labels (in geojson format)."""
         # Create a mask layer out of the geojson
         mask_geojson_fn = os.path.join(
@@ -367,7 +380,7 @@ def _load_mask(self) -> Tensor:
             labels,
             out_shape=(self.tile_height, self.tile_width),
             fill=0,  # nodata value
-            transform=self.tile_transform,
+            transform=transform,
             all_touched=False,
             dtype=np.uint8,
         )