[gdal-dev] HFA (.img) driver prints Warning 1: NaN converted to INT_MAX when float raster has nan as the NoData value

[Jason Roberts]

Hi GDAL team,

I'm working with the GDAL Python API. I have some HFA (.img) files that 
are float32 and that use nan as their NoData value. As far as I can 
tell, using nan is allowed but I could be wrong. When I open them, I get 
"Warning 1: NaN converted to INT_MAX." Everything seems to work fine 
after that. Is this message something I need to worry about? If not, may 
I suggest you remove it from the HFA driver if possible?

Here's some code demonstrating the message. If need be, I can provide an 
example file, or write some code to generate one.

 >>> import numpy as np
 >>> from osgeo import gdal
 >>> gdal.__version__       # this version is packaged with ArcGIS Pro 
3.4, but I don't think the version matters
'3.9.2e'
 >>> ds = 
gdal.Open(r'\\conch\denmod\Covariates\NARW25\CMEMS_GLORYS\SST\1999\SST_199901.img', 
gdal.GA_ReadOnly)
Warning 1: NaN converted to INT_MAX.
 >>> band = ds.GetRasterBand(1)
 >>> gdal.GetDataTypeName(band.DataType)
'Float32'
 >>> band.GetNoDataValue()
nan
 >>> arr = band.ReadAsArray()   # the data look ok:
 >>> np.isnan(arr).sum()
86788
 >>> (~np.isnan(arr)).sum()
142985
 >>> np.max(arr)
nan
 >>> np.nanmax(arr)
27.078554

As far as I can tell, the warning comes from this code in 
gdal/frmts/hfa/hfafield.cpp:

                 else if (std::isnan(dfDoubleRet))
                 {
                     CPLError(CE_Warning, CPLE_AppDefined,
                              "NaN converted to INT_MAX.");
                     nIntRet = nMax;
                 }

But I don't know if there are any negative ramifications that will result.

Thank you for your help. And, as always, thank you very much for 
developing and maintaining GDAL.

Jason
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