Dear all,
I think these attributes would be more appropriately dealt with in the definition of the quantity - i.e. held with the standard_name or other fixed vocabulary metadata. It is very unlikely to change quickly and can therefore be considered as fixed, in which case it would not be needed in every NetCDF file containing that variable. However, perhaps this approach is less workable than something you can put in the NetCDF variable metadata.
Cheers,
Ag
-----Original Message-----
From: cf-metadata-bounces at cgd.ucar.edu on behalf of Roy Lowry
Sent: Thu 21/12/2006 9:48 AM
To: cf-metadata at cgd.ucar.edu; jdb at mail.nerc-essc.ac.uk
Subject: Re: [CF-metadata] attributes for min/max data values for visualization
Dear All,
I'm not sure how this would work because the valid range could be a function of both the Standard Name and the Cell Method.
Cheers, Roy.
>>> "Jon Blower" <jdb at mail.nerc-essc.ac.uk> 12/21/2006 9:35 am >>>
Dear all,
As some of you know, we at Reading have developed an online,
interactive visualization tool for CF-compliant NetCDF data
(
http://lovejoy.nerc-essc.ac.uk:8080/ncWMS/godiva2.html). In order to
create images of the data that are stored in the NetCDF files, the
tool needs to know a sensible range of possible data values. For
example, for sea temperature a sensible range is -5 to 35 C.
Many data files specify the valid_min and valid_max attributes: these
define the range of all possible values - outside this range, data are
interpreted as missing values and are thus "hard" boundaries. This
range is often set very wide to ensure that no true data values are
interpreted as missing.
I think it would be useful if there were a similar pair of attributes
(say "suggested_min" and "suggested_max") that are interpreted by
visualization tools as clues to generating a sensible colour scale,
but values outside this range are not interpreted as missing.
Do others think this is sensible, and is there anything similar existing in CF?
Thanks,
Jon
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Reading e-Science Centre Fax: +44 118 378 6413
ESSC Email: jdb at mail.nerc-essc.ac.uk
University of Reading
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Received on Thu Dec 21 2006 - 02:54:07 GMT
