Hi Sean,
>From your description, it sounds like you're confusing valid_min and valid_max
with actual_min and actual_max. The former attributes define theoretical
extrema, beyond which data is considered invalid (e.g., latitude > 90 degrees
or precipitation < 0). The latter are what modelers would include if they were
providing information to assist with visualizations.
Personally, I dislike actual_min and actual_max, because I don't think you can
trust them to be correct. But if you want to take advantage of visualization
hints in metadata, those are the attributes to reference.
Cheers,
--Seth
====
Seth McGinnis
NARCCAP Data Manager
Associate Scientist
IMAGe / NCAR
=====
On Thu, 19 Apr 2012 16:13:51 +0100
"Gaffney, Sean P." <sgaf at bodc.ac.uk> wrote:
>Hi all,
>
>My name is Sean Gaffney, from the British Oceanographic Data Centre, and I'm
>working on a project dealing with numerical model data that are in CF
>compliant NetCDF, so I thought I'd sign up to the community.
>
>The project I am working on aims to develop a web-based delivery system for
>oceanographic numerical model data and has a module which allows visualisation
>of the data. We've been using test CF data to fine-tune some of the technical
>aspects of this visualisation.
>
>I have a particular issue at the moment which I hope someone out there might
>be able to assist me with.
>
>My problem started when I found that the test CF data were passing the BADC CF
>compliance checker, but not visualising properly. A check with the people who
>developed the visualisation module led to the discovery that, while the CF
>metadata were formatted correctly, the actual values within the metadata were
>incorrect e.g. the valid_min and valid_max attributes for both the latitude
>and longitude and dimensional variables had values which did not reflect the
>actual range of data in the file. The visualisation was setting itself up
>based on the values stored in the attributes and was therefore not displaying
>any data.
>
>Has anyone in the CF community come across this sort of issue before and if
>so, what solutions would you recommend? My initial thoughts were that I'd have
>to develop some sort of code which interrogates the data file and compares the
>entries in the CF metadata header against the actual data values in the file,
>but I'd be interested to see what people think. Please bear in mind that I
>won't actually be generating model runs myself, but will be receiving data
>from people that have done so and need to know that I'm being given valid data
>and metadata.
>
>Sorry for making my first message to the CF community so long.
>
>Looking forward to your responses
>
>Yours
>
>Sean Gaffney
>BODC
>
>
>--------------------------------------------------------------------------------
>Sean Gaffney
>Data Scientist
>British Oceanographic Data Centre
>Joseph Proudman Building
>6 Brownlow Street
>Liverpool
>L3 5DA
>UK
>+44 (0)151 795 4950
>
>
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Received on Thu Apr 19 2012 - 14:04:51 BST
