Keep temp and dest region arrays to same shape in merge

Resolves #2202

CHANGES.txt

@@ -1,6 +1,11 @@
 Changes
 =======
 
+1.2.5 (TBD)
+-----------
+
+- Prevent a rare merge error (#2202).
+
 1.2.4 (2021-05-31)
 ------------------
 

rasterio/__init__.py

@@ -40,7 +40,7 @@
 import rasterio.path
 
 __all__ = ['band', 'open', 'pad', 'Env']
-__version__ = "1.2.4"
+__version__ = "1.2.5dev"
 __gdal_version__ = gdal_version()
 
 # Rasterio attaches NullHandler to the 'rasterio' logger and its

rasterio/merge.py

@@ -70,6 +70,7 @@ def merge(
     output_count=None,
     resampling=Resampling.nearest,
     method="first",
+    target_aligned_pixels=False,
     dst_path=None,
     dst_kwds=None,
 ):
@@ -217,29 +218,26 @@ def nullcontext(obj):
             ys.extend([bottom, top])
         dst_w, dst_s, dst_e, dst_n = min(xs), min(ys), max(xs), max(ys)
 
-    logger.debug("Output bounds: %r", (dst_w, dst_s, dst_e, dst_n))
-    output_transform = Affine.translation(dst_w, dst_n)
-    logger.debug("Output transform, before scaling: %r", output_transform)
-
     # Resolution/pixel size
     if not res:
         res = first_res
     elif not np.iterable(res):
         res = (res, res)
     elif len(res) == 1:
         res = (res[0], res[0])
-    output_transform *= Affine.scale(res[0], -res[1])
-    logger.debug("Output transform, after scaling: %r", output_transform)
+
+    if target_aligned_pixels:
+        dst_w = math.floor(dst_w / res[0]) * res[0]
+        dst_e = math.ceil(dst_e / res[0]) * res[0]
+        dst_s = math.floor(dst_s / res[1]) * res[1]
+        dst_n = math.ceil(dst_n / res[1]) * res[1]
 
     # Compute output array shape. We guarantee it will cover the output
     # bounds completely
-    output_width = int(math.ceil((dst_e - dst_w) / res[0]))
-    output_height = int(math.ceil((dst_n - dst_s) / res[1]))
+    output_width = int(round((dst_e - dst_w) / res[0]))
+    output_height = int(round((dst_n - dst_s) / res[1]))
 
-    # Adjust bounds to fit
-    dst_e, dst_s = output_transform * (output_width, output_height)
-    logger.debug("Output width: %d, height: %d", output_width, output_height)
-    logger.debug("Adjusted bounds: %r", (dst_w, dst_s, dst_e, dst_n))
+    output_transform = Affine.translation(dst_w, dst_n) * Affine.scale(res[0], -res[1])
 
     if dtype is not None:
         dt = dtype
@@ -314,23 +312,29 @@ def nullcontext(obj):
             )
 
             # 4. Read data in source window into temp
-            src_window = src_window.round_shape(pixel_precision=0)
-            dst_window = dst_window.round_shape(pixel_precision=0)
-            trows, tcols = dst_window.height, dst_window.width
-            temp_shape = (src_count, trows, tcols)
-            temp = src.read(
+            src_window_rnd_shp = src_window.round_shape(pixel_precision=0)
+            dst_window_rnd_shp = dst_window.round_shape(pixel_precision=0)
+            dst_window_rnd_off = dst_window_rnd_shp.round_offsets(pixel_precision=0)
+            temp_height, temp_width = (
+                dst_window_rnd_off.height,
+                dst_window_rnd_off.width,
+            )
+            temp_shape = (src_count, temp_height, temp_width)
+            temp_src = src.read(
                 out_shape=temp_shape,
-                window=src_window,
+                window=src_window_rnd_shp,
                 boundless=False,
                 masked=True,
                 indexes=indexes,
                 resampling=resampling,
             )
 
         # 5. Copy elements of temp into dest
-        dst_window = dst_window.round_offsets(pixel_precision=0)
-        roff, coff = dst_window.row_off, dst_window.col_off
-        region = dest[:, roff:roff + trows, coff:coff + tcols]
+        roff, coff = (
+            max(0, dst_window_rnd_off.row_off),
+            max(0, dst_window_rnd_off.col_off),
+        )
+        region = dest[:, roff : roff + temp_height, coff : coff + temp_width]
 
         if math.isnan(nodataval):
             region_mask = np.isnan(region)
@@ -339,8 +343,9 @@ def nullcontext(obj):
         else:
             region_mask = region == nodataval
 
+        # Ensure common shape, resolving issue #2202.
+        temp = temp_src[:, : region.shape[1], : region.shape[2]]
         temp_mask = np.ma.getmask(temp)
-
         copyto(region, temp, region_mask, temp_mask, index=idx, roff=roff, coff=coff)
 
     if dst_path is None:

tests/test_merge.py

@@ -1,5 +1,8 @@
 """Tests of rasterio.merge"""
 
+import boto3
+from hypothesis import given, settings
+from hypothesis.strategies import floats
 import numpy
 import pytest
 
@@ -58,11 +61,46 @@ def test_issue2163():
     with rasterio.open("tests/data/float_raster_with_nodata.tif") as src:
         data = src.read()
         result, transform = merge([src])
-        assert numpy.allclose(data, result)
+        assert numpy.allclose(data, result[:, : data.shape[1], : data.shape[2]])
 
 
 def test_unsafe_casting():
     """Demonstrate fix for issue 2179"""
     with rasterio.open("tests/data/float_raster_with_nodata.tif") as src:
         result, transform = merge([src], dtype="uint8", nodata=0.0)
         assert not result.any()  # this is why it's called "unsafe".
+
+
+@pytest.mark.skipif(
+    not (boto3.Session()._session.get_credentials()),
+    reason="S3 raster access requires credentials",
+)
+@pytest.mark.network
+@pytest.mark.slow
+@settings(deadline=None, max_examples=5)
+@given(
+    dx=floats(min_value=-0.05, max_value=0.05),
+    dy=floats(min_value=-0.05, max_value=0.05),
+)
+def test_issue2202(dx, dy):
+    import rasterio.merge
+    from shapely import wkt
+    from shapely.affinity import translate
+
+    aoi = wkt.loads(
+        r"POLYGON((11.09 47.94, 11.06 48.01, 11.12 48.11, 11.18 48.11, 11.18 47.94, 11.09 47.94))"
+    )
+    aoi = translate(aoi, dx, dy)
+
+    with rasterio.Env(AWS_NO_SIGN_REQUEST=True,):
+        ds = [
+            rasterio.open(i)
+            for i in [
+                "/vsis3/copernicus-dem-30m/Copernicus_DSM_COG_10_N47_00_E011_00_DEM/Copernicus_DSM_COG_10_N47_00_E011_00_DEM.tif",
+                "/vsis3/copernicus-dem-30m/Copernicus_DSM_COG_10_N48_00_E011_00_DEM/Copernicus_DSM_COG_10_N48_00_E011_00_DEM.tif",
+            ]
+        ]
+        aux_array, aux_transform = rasterio.merge.merge(datasets=ds, bounds=aoi.bounds)
+        from rasterio.plot import show
+
+        show(aux_array)