Re: [Geopriv] Fw: New Version Notificationfordraft-mayrhofer-geopriv-geo-uri-00

Carl, thanks for the review and the suggestions.

comments inline.

> Apologies for the delay in providing comments. Hope the
> following helps.
>
> 1. You need to be much more specific about the use of WGS 84.
> In order to be as clear as possible, I would suggest using
> the following words:
>
> Geographic locations in this document are defined using WGS
> 84 (World Geodetic System 1984), equivalent to the OGP
> Surveying & Positioning Committee EPSG code 4326 (2
> dimensions). This document does not assign responsibilities
> for coordinate transformations from and to other Spatial
> Reference Systems. A WGS-84 coordinate value is here
> represented as a comma-delimited latitude/longitude pair,
> measured in decimal degrees (un-projected). Latitudes range
> from -90 to 90 and longitudes range from -180 to 180.
> Coordinates in the Southern and Western hemispheres are
> signed negative with a leading dash. http://www.epsg.org/
>
> There is also now an on-line registry of the EPSG database so
> the exact parameters for the WGS-84 - 2d datum can be referenced.

I guess we'll add most that text to the next revision, and your name to
the acknowledgement section :)

> 2. I think "altitude" needs to be a bit more clerly and
> consistently defined. In one place the document mentions
> "mean sea level" and in another "earth's surface".

point taken, will improve for the next revision
 
> 3. You might want to check out
> http://tools.ietf.org/html/draft-daviel-http-geo-header-05 .
> Similar but different approach to the same problem. For
> example, the authors of this document do address to a certain
> extent civic addresses as well as uncertaintly. This document
> is targeted a bit more at the geo-enabled mobile community.

I know that document, i did talk to Andrew on the IETF back in Vancouver
about this. It tackles a similar problem space, but is limited to a
certain protocol. I think i remember he was asked to move more towards
the PIDF-LO (CAtype) formats during the last Geopriv session..

> 4. Back to WGS. Might want to mention that WGS stands for
> World Geodetic System. Also, WGS-84 predates GPS but GPS was
> used to upgrade WGS-84.

thanks - i guess you noticed i'm not a geodetic pro :)

> From US National Geodetic Survey: WGS 84 is the World
> Geodetic System of 1984. It is the reference frame used by
> the U.S. Department of Defense (DoD) and is defined by the
> National Geospatial-Intelligence Agency(NGA
> <http://www.nga.mil/> ) (formerly the National Imagery and
> Mapping Agency) (formerly the Defense Mapping Agency). WGS 84
> is used by DoD for all its mapping, charting, surveying, and
> navigation needs, including its GPS "broadcast" and "precise"
> orbits. WGS 84 was defined in January 1987 using Doppler
> satellite surveying techniques. It was used as the reference
> frame for broadcast GPS Ephemerides (orbits) beginning
> January 23, 1987. At 0000 GMT January 2, 1994, WGS 84 was
> upgraded in accuracy using GPS measurements. The formal name
> then became WGS 84 (G730) since the upgrade date coincided
> with the start of GPS Week 730. It became the reference frame
> for broadcast orbits on June 28, 1994. At 0000 GMT September
> 30, 1996 (the start of GPS Week 873), WGS 84 was redefined
> again and was more closely aligned with International Earth
> Rotation Service (IERS) Terrestrial Reference Frame (ITRF)
> 94. It is now formally called WGS 84 (G873). WGS 84 (G873)
> was adopted as the reference frame for broadcast orbits on
> January 29, 1997.
>
> 5. You might also want to check out how geo lat-long are
> being expressed (proposal) as part of OpenSearch and GeoJSON.
> http://www.opensearch.org/Specifications/OpenSearch/Extensions
> /Geo/1.0/Draft_1 . I have concerns that multiple methods of
> expression are emerging. A killer for interoperability.

I definitely agree - however, all formats that use simple lat/lon in
WGS84 can nicely interoperate. And, the primary goal for the URI is to
refer to something of the user's choice - a browser with "geo:" support
could offer a search on OpenSearches that are geo-enabled, for example
(like operator offers various ways to use a location today).

thanks for the comments!

Alex
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Received on Wed, 28 May 2008 10:39:26 +0200