[gdal-dev] Overviews are not taken into account while reading with specified resampling method

[Denis Rykov]

I have remote *.vrt raster and *.vrt.ovr accessible through HTTP. When I
run the following script with rasterio:

with rasterio.open("http://*.vrt"") as src:
    image = src.read(indexes=[1, 2, 3], **{
        "window": Window(col_off=6961, row_off=105176, width=5671, height=5648),
        "resampling": Resampling.cubic,
        "boundless": True,
        "out_shape": (3, 383, 385),
        "masked": True
    })

depending on "resampling" algorithm GDAL sends different amounts of
requests to the server. In the case of "cubic" it doesn't take into account
overviews and sends requests directly to *.tif files (900 in my case). In
case of "nearest" everything is ok (only 60 requests, *.vrt.ovr is taken
into account).

Does GDAL check the resampling algorithm of overviews and in case it
differs from the option specified in read() method they are bypassed or it
works differently?
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