fix for float NaN nodata (#691)

* fix for float NaN nodata

* update changelog

---------

Co-authored-by: vincentsarago <vincent.sarago@gmail.com>

CHANGES.md

@@ -1,4 +1,8 @@
 
+# 6.4.4 (2024-04-02)
+
+* better handler `NaN` nodata values for masking (author @cerolinx, https://github.com/cogeotiff/rio-tiler/pull/691)
+
 # 6.4.3 (2024-03-22)
 
 * make sure `scale` and `offset` are set in `Info` even when `offset=0.` or `scale=1.0` (https://github.com/cogeotiff/rio-tiler/pull/687)

rio_tiler/reader.py

@@ -238,7 +238,10 @@ def read(
 
             # if data has Nodata then we simply make sure the mask == the nodata
             if nodata is not None:
-                data.mask = data.data == nodata
+                if numpy.isnan(nodata):
+                    data.mask = numpy.isnan(data.data)
+                else:
+                    data.mask = data.data == nodata
 
         stats = []
         for ix in indexes:

tests/test_reader.py

@@ -34,6 +34,9 @@
 COG_SCALE = os.path.join(os.path.dirname(__file__), "fixtures", "cog_scale.tif")
 COG_CMAP = os.path.join(os.path.dirname(__file__), "fixtures", "cog_cmap.tif")
 COG_NODATA = os.path.join(os.path.dirname(__file__), "fixtures", "cog_nodata.tif")
+COG_NODATA_FLOAT_NAN = os.path.join(
+    os.path.dirname(__file__), "fixtures", "cog_nodata_float_nan.tif"
+)
 
 
 @pytest.fixture(autouse=True)
@@ -848,3 +851,11 @@ def test_nodata_orverride():
         prev = reader.read(src_dst, max_size=100, nodata=2720)
         assert prev.mask[0, 0] == 255
         assert not numpy.all(prev.mask)
+
+
+def test_tile_read_nodata_float():
+    """Should work as expected when using NaN as nodata value."""
+    with rasterio.open(COG_NODATA_FLOAT_NAN) as src_dst:
+        prev = reader.read(src_dst, max_size=100)
+        assert prev.mask[0, 0] == 0
+        assert not numpy.all(prev.mask)