[Esip-documentation] Geospatial Bounds

[John Graybeal via Esip-documentation]

On Oct 2, 2014, at 09:18, Aleksandar Jelenak via Esip-documentation <esip-documentation at lists.esipfed.org> wrote:

> The geospatial_bounds attribute’s role is to broadcast data’s geospatial
> extent to metadata cataloging systems. If the data is in some other CRS then it is up to the data producer (creator) or publisher to translate that geospatial extent to the WGS-84 2D or 3D CRSs for this attribute. To me that is a more reasonable requirement then to expect metadata discovery systems to know all the possible CRSs.

OK, thanks for these clarifications, Aleksandar.  I know it bothers people to add attributes. But for the record, I agree with David N's comment, that this makes sense for some parts of the community but not others.  (Because distances above and below actual surface level are not meaningful in summary, once translated to an ellipsoid-based height.) Plus, it will look odd if the geospatial limits (also for metadata catalog systems) are following one vertical CRS, while the bounding box follows another?  

In researching this, it turns out there is already an attribute for this in 1.1; we lost the meaning during the 1.3 transition. For geospatial_vertical_units it used to say "Further refinement of the geospatial bounding box…", and the mapping examples pointed to vertical CRS.  If we follow our "return to 1.1" philosophy, I think this definition needs to be something like this:
> Units for the vertical axis described in "geospatial_vertical_min", "geospatial_vertical_max", and "geospatial_bounding_box" 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. Example: "EPSG 5829" (instantaneous height above sea level) or "EPSG 5831" (instantaneous depth below sea level).

Ha. Sorry for missing the 10 AM deadline. :-)

John

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