[netcdfgroup] Potential inconsistency in NUG Attribute Conventions

• To: netcdfgroup@xxxxxxxxxxxxxxxx
• Subject: [netcdfgroup] Potential inconsistency in NUG Attribute Conventions
• From: Sergey Panov <sergey.panov@xxxxxxxxxxx>
• Date: Wed, 03 Dec 2008 00:45:39 -0500

I want to be able to use unsigned byte and/or unsigned short integers to
store "compressed" data. Under "compressed" I mean floating point values
mapped into integer values via the 'scale_factor' and 'add_offset'
attributes.

The description of the deprecated 'signedness' attribute states:
"Deprecated attribute, originally designed to indicate whether byte
values should be treated as signed or unsigned. The attributes
'valid_min' and 'valid_max' may be used for this purpose. For example,
if you intend that a byte variable store only nonnegative values, you
can use 'valid_min' = 0 and 'valid_max' = 255. This attribute is ignored
by the netCDF library."

How that scheme is supposed to work with 'scale_factor' != 1 and
'add_offset' != 0 ? It would have been simple if 'valid_range' was
referring to the stored, not yet unpacked(unscaled) variables, but it
does not seems to be the case.


Regards,
         Sergey Panov

• Follow-Ups:
  • Re: [netcdfgroup] Potential inconsistency in NUG Attribute Conventions
    • From: Timothy Hume