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." <[email protected]> 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 > > >-- >This message (and any attachments) is for the recipient only. NERC >is subject to the Freedom of Information Act 2000 and the contents >of this email and any reply you make may be disclosed by NERC unless >it is exempt from release under the Act. Any material supplied to >NERC may be stored in an electronic records management system. >_______________________________________________ >CF-metadata mailing list >[email protected] >http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
