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

Wed Feb 25 13:59:29 EST 2015

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>  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 list
>>> Esip-documentation at lists.esipfed.org
>>> http://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 list
> Esip-documentation at lists.esipfed.org
> http://lists.deltaforce.net/mailman/listinfo/esip-documentation

-- 
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