NUG convention valid_min not supported without valid_max

[magnusuMET]

The valid_min attribute is not respected when given by itself, but only when valid_max is also provided

rio-tiler/rio_tiler/io/xarray.py

Line 296 in deb5f3b

if minv is not None and maxv is not None and nodata not in [minv, maxv]:

The conventions does not state valid_max is necessary and I would expect data below valid_min to be masked

[vincentsarago]

valid_min and valid_max are only used as statistics within rio-tiler (we use them for automatic rescaling if needed when rendering an image. We don't use it for masking, which should be handled in rioxarray

rio-tiler/rio_tiler/io/xarray.py

Line 299 in deb5f3b

arr = da.to_masked_array()

[magnusuMET]

Thanks for the reply. I have misunderstood the role of the attributes as I was hoping values below valid_min would be masked away. This is not what is done by xarray so rio_tiler behaves correctly in this regard