[Esip-documentation] ACDD-1.3 documentation change request: Descriptions of "resolution" attributes

David Neufeld - NOAA Affiliate david.neufeld at noaa.gov
Wed Feb 25 19:43:33 EST 2015 

Bob I think you've made a good summary about how standards development and
discussions often occur in our community, however I also like to think that
new ideas and contributions are welcomed and even encouraged!  A discussion
list seems like the right place to put those ideas forward even though they
may not ultimately be accepted.

Dave

On Wed, Feb 25, 2015 at 2:07 PM, Bob Simons - NOAA Federal via
Esip-documentation <esip-documentation at lists.esipfed.org> wrote:

> Aaron, please understand that ACDD, like CF, is a standard. Successive
> versions of the standard are hammered out by seemingly endless discussions
> and numerous votes (with the hope of reaching consensus) by people in the
> community. Once a version of a standard is ratified (as ACDD 1.3 is), you
> should treat it as if that version were written in stone. Software (like
> ncISO, THREDDS, ERDDAP) is written to work according to the standard, not
> the other way around (unless it is something new that is being added to the
> standard). And if you don't like an attribute's name, (to be blunt) tough.
> It is what it is. You could have lobbied for some other name before the
> attribute first made it into ACDD. But now that it is in ACDD, please don't
> advocate changing it just because you think a slightly different name is
> more appropriate. Lots of software and thousands of datasets have been
> written to follow the ACDD standard. They shouldn't have to change just
> because you think a slightly different name is more appropriate. That's why
> we try hard to get standards right the first time. That's why we try very
> hard not to make changes to successive versions of ACDD (and other
> standards) that conflict with previous versions.
>
>
>
> On Wed, Feb 25, 2015 at 12:29 PM, Aaron Sweeney via Esip-documentation <
> esip-documentation at lists.esipfed.org> wrote:
>
>>  Hi, John,
>>
>>      Why are these attributes not called
>> "geospatial_[lat|lon|vertical]_spacing", rather than
>> "geospatial_[lat|lon|vertical]_resolution", if, in fact, the intention, as
>> indicated in their Descriptions, is to capture the "targeted spacing of
>> points"?
>>
>>      My first inclination, upon reading the name of the attribute
>> "geospatial_[lat|lon|vertical]_resolution", was to interpret it to mean
>> "how well the numerical value of [lat|lon|vertical] is resolved."
>>
>> Cordially,
>> Aaron
>>
>>
>>
>>
>> On 02/25/2015 01:19 PM, John Graybeal via Esip-documentation wrote:
>>
>> I am trying to find a good ncISO rep to be a part of this discussion --
>> with luck David Neufeld will jump in soon, or people can suggest another
>> rep, perhaps from Unidata?
>>
>>  Not sure yet if we're having a call tomorrow, for now I am assuming we
>> are.
>>
>>  I'm not sure that many current users are using this value the way it is
>> documented: "Information about the targeted spacing of points". That does
>> not mean either the accuracy or precision of the value, but the (intended)
>> distance between points in a grid of values -- but often these values
>> appear in data sets for single fixed stations, which seems invalid.
>>
>>  And as Jim B points out (thank you), the original ISO mapping assumes
>> the grid sizes are georectified -- but some/many grids in earth science are
>> laid out in non-angular constant steps (meters). I assumed we want to
>> support those cases, and no one found fault with the examples -- but maybe
>> they are flawed, if georectified is a constraint. Alternatively, units of
>> meters (or plain, non-geo degree) could be mapped to non-georectified ISO
>> grid resolution terms.
>>
>>  John
>>
>>  On Feb 25, 2015, at 10:59, Jim Biard via Esip-documentation <
>> esip-documentation at lists.esipfed.org> wrote:
>>
>>  Hi.
>>
>> I checked this as well, and there should clearly be both a floating-point
>> number and a units for a resolution entry. As Aaron showed in his email,
>> the units go in a 'uom' attribute on the gco:Measure element, and the
>> number is the value of the element. If ncISO isn't doing this, then that
>> sure appears to be an ncISO bug.
>>
>> There is another issue, of a sort, that this points up. The
>> geospatial_(lat/lon)_resolution attributes in the documentation Aaron
>> listed allow for units that are nonsensical (to me, anyway), such as meters
>> for a quantity that should be restricted to angular units. You can get away
>> with it for latitude, but there is no way to create a longitude axis on a
>> grid that has constant steps in non-angular units.
>>
>> Grace and peace,
>>
>> Jim
>>
>> On 2/25/15 12:32 PM, Aaron Sweeney via Esip-documentation wrote:
>>
>> Hi, Bob et al.,
>>
>>      I believe that these resolutions are currently mapped to ISO 19115-2
>> gco:Measures <https://geo-ide.noaa.gov/wiki/index.php?title=Measure>, as
>> in:
>>
>> geospatial_lat_resolution -->
>> <gco:Measure
>> uom="[geospatial_lat_unit]">[geospatial_lat_resolution]</gco:Measure>
>>
>> geospatial_lon_resolution -->
>> <gco:Measure
>> uom="[geospatial_lon_unit]">[geospatial_lon_resolution]</gco:Measure>
>>
>> geospatial_vertical_resolution -->
>> <gco:Measure
>> uom="[geospatial_vertical_unit">[geospatial_vertical_resolution]</gco:Measure>
>>
>> The GEO-IDE wiki page on gco:Measure (link above) indicates that the
>> value should be an "XML Schema double."
>>
>>      Also, the earlier ACDD-1.1 documentation includes the ISO 19115-2
>> path as:
>>
>> /gmi:MI_Metadata/gmd:spatialRepresentationInfo/gmd:MD_Georectified/gmd:axisDimensionProperties/gmd:MD_Dimension/gmd:resolution/gco:Measure
>>
>> Cordially,
>> Aaron
>>
>> On 02/25/2015 10:17 AM, Bob Simons - NOAA Federal wrote:
>>
>> Is that an error in ACDD or in ncISO? (I don't know. I think it is
>> debatable.) It is probably easier to change ncISO than to change ACDD
>> (at least until the next version which is probably far off) and all
>> datasets which follow the recommendations of the ACDD documentation.
>>
>> On Wed, Feb 25, 2015 at 9:11 AM, Aaron Sweeney via Esip-documentation<esip-documentation at lists.esipfed.org> <esip-documentation at lists.esipfed.org> wrote:
>>
>>  Hi, folks,
>>
>>       I want to bring to your attention a problem with the ACDD-1.3
>> documentation that is leading to the creation of invalid ISO 19115-2
>> metadata records.
>>
>>       Specifically, I am referring to the Descriptions of the following
>> Suggested global attributes: geospatial_lat_resolution,
>> geospatial_lon_resolution, and geospatial_vertical_resolution.  For
>> reference and clarity, I've included these attributes (as well as their
>> related units attributes) and their descriptions from the ACDD-1.3
>> documentation below this message.
>>
>>       There are two problems with the Description of these "resolutions."
>> The first is the recommendation to include both a numerical value and unit.
>> The ncISO tool expects these resolutions to be numeric only.  This leads to
>> the creation of invalid ISO 19115-2 records.  The second problem is that the
>> Description does not require the unit of resolution to be the same as the
>> corresponding "geospatial_[lat|lon|vertical]_unit."
>>
>>       I would advocate that the Description of resolution explicitly state
>> that a numeric value is expected and that the value be expressed in the same
>> unit as specified in the corresponding "geospatial_[lat|lon|vertical]_unit"
>> attribute.
>>
>> Cordially,
>> Aaron
>>
>> ----relevant ACDD-1.3 documentation follows----
>>
>> geospatial_lat_units: Units for the latitude axis described in
>> "geospatial_lat_min" and "geospatial_lat_max" attributes. These are presumed
>> to be "degree_north"; other options from udunits may be specified instead.
>> geospatial_lat_resolution: Information about the targeted spacing of points
>> in latitude. Recommend describing resolution as a number value followed by
>> the units. Examples: '100 meters', '0.1 degree'
>> geospatial_lon_units: Units for the longitude axis described in
>> "geospatial_lon_min" and "geospatial_lon_max" attributes. These are presumed
>> to be "degree_east"; other options from udunits may be specified instead.
>> geospatial_lon_resolution: Information about the targeted spacing of points
>> in longitude. Recommend describing resolution as a number value followed by
>> units. Examples: '100 meters', '0.1 degree'
>> geospatial_vertical_units: Units for the vertical axis described in
>> "geospatial_vertical_min" and "geospatial_vertical_max" attributes. The
>> default is EPSG:4979 (height above the ellipsoid, in meters); other vertical
>> coordinate reference systems may be specified. Note that the common
>> oceanographic practice of using pressure for a vertical coordinate, while
>> not strictly a depth, can be specified using the unit bar. Examples:
>> 'EPSG:5829' (instantaneous height above sea level), 'EPSG:5831'
>> (instantaneous depth below sea level).
>> geospatial_vertical_resolution: Information about the targeted vertical
>> spacing of points. Example: '25 meters'
>>
>>
>>
>> --
>> Aaron D. Sweeney
>> Water Level Data Manager
>>
>> Cooperative Institute for Research in Environmental Sciences (CIRES)
>> University of Colorado at Boulder
>> and
>> NOAA National Geophysical Data Center
>> Marine Geology and Geophysics Division
>> 325 Broadway, E/GC3
>> Boulder, CO 80305-3328
>>
>> Phone: 303-497-4797, Fax: 303-497-6513
>>
>> DISCLAIMER: The contents of this message are mine personally and do not
>> necessarily reflect any position of NOAA.
>>
>>
>> _______________________________________________
>> Esip-documentation mailing listEsip-documentation at lists.esipfed.orghttp://lists.deltaforce.net/mailman/listinfo/esip-documentation
>>
>>
>> --
>> Aaron D. Sweeney
>> Water Level Data Manager
>>
>> Cooperative Institute for Research in Environmental Sciences (CIRES)
>> University of Colorado at Boulder
>> and
>> NOAA National Geophysical Data Center
>> Marine Geology and Geophysics Division
>> 325 Broadway, E/GC3
>> Boulder, CO 80305-3328
>>
>> Phone: 303-497-4797, Fax: 303-497-6513
>>
>> DISCLAIMER: The contents of this message are mine personally and do not necessarily reflect any position of NOAA.
>>
>>
>>
>> _______________________________________________
>> Esip-documentation mailing listEsip-documentation at lists.esipfed.orghttp://lists.deltaforce.net/mailman/listinfo/esip-documentation
>>
>>
>> --
>>       <igjdgbcb.png> <http://www.cicsnc.org/> Visit us on
>>  Facebook <http://www.facebook.com/cicsnc>   *Jim Biard*
>> *Research Scholar*
>>  Cooperative Institute for Climate and Satellites NC <http://cicsnc.org/>
>>  North Carolina State University <http://ncsu.edu/>
>>  NOAA's National Climatic Data Center <http://ncdc.noaa.gov/>
>> 151 Patton Ave, Asheville, NC 28801
>> e: jbiard at cicsnc.org
>> o: +1 828 271 4900
>>
>>
>>
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>>
>>
>> _______________________________________________
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>>
>>
>> --
>> Aaron D. Sweeney
>> Water Level Data Manager
>>
>> Cooperative Institute for Research in Environmental Sciences (CIRES)
>> University of Colorado at Boulder
>> and
>> NOAA National Geophysical Data Center
>> Marine Geology and Geophysics Division
>> 325 Broadway, E/GC3
>> Boulder, CO 80305-3328
>>
>> Phone: 303-497-4797, Fax: 303-497-6513
>>
>> DISCLAIMER: The contents of this message are mine personally and do not necessarily reflect any position of NOAA.
>>
>>
>> _______________________________________________
>> Esip-documentation mailing list
>> Esip-documentation at lists.esipfed.org
>> http://lists.deltaforce.net/mailman/listinfo/esip-documentation
>>
>>
>
>
> --
> Sincerely,
>
> Bob Simons
> IT Specialist
> Environmental Research Division
> NOAA Southwest Fisheries Science Center
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>
> The contents of this message are mine personally and
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> Government or the National Oceanic and Atmospheric Administration.
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