COGReader.tile doesn't take into account mask band in some circumstances

There is following set of files:

• masked.tif (with PER_DATASET internal mask)
• data.vrt built based on masked.tif
• data.vrt.ovr (external overviews)

Let’s try to render a tile out of it:

In [1]: from rio_tiler.io import COGReader

In [2]: with COGReader("/tmp/test/data.vrt") as cog:
   ...:     tile = cog.tile(2323, 3503, 13, tilesize=256)
   ...: 
GDAL: GDALClose(/tmp/test/masked.tif, this=0x3699940)
GDAL: GDALClose(/tmp/test/data.vrt, this=0x3640b10)

In [3]: with open("/tmp/test/tile-ok.png", "wb") as dst:
   ...:     dst.write(tile.render())

Expected result (screenshot from QGIS):

Actual result:

Everything is fine.

Now let’s try to render tile on a lower zoom level, in this case GDAL will use existing overviews.

In [1]: from rio_tiler.io import COGReader

In [2]: with COGReader("/tmp/test/data.vrt") as cog:
   ...:     tile = cog.tile(72, 109, 8, tilesize=256)
   ...: 
GDAL: GDALClose(/tmp/test/masked.tif, this=0x2f1f7e0)
GDAL: GDALClose(/tmp/test/data.vrt, this=0x20b6740)
GDAL: GDALClose(/tmp/test/data.vrt.ovr, this=0x2e51cc0)

In [3]: with open("/tmp/test/tile-nok.png", "wb") as dst:
   ...:     dst.write(tile.render())
   ...: 

Expected result:

Actual result:

As you can see the mask has not been taken into account.

Files that are being used: example.zip

[drnextgis]

In [1]: import rasterio, rio_tiler, platform

In [2]: rasterio.__version__
Out[2]: '1.2.6'

In [3]: rio_tiler.__version__
Out[3]: '2.0.8'

In [4]: rasterio.gdal_version()
Out[4]: '3.3.0'

In [5]: platform.system()
Out[5]: 'Linux'

[drnextgis]

It did the trick!