The official EPSG CRS registry is here http://www.epsg-registry.org/
and the OGC urn resolver (beta) is here: http://urn.opengis.net/
Please note that the OGC urn registry against which the resolver works has
not been fully. Should be in the next few months. There are also seveal
OGC standards documents that specify the rules for the "def" branch of the
OGC urn - including type "crs".
Alexandre is correct - there are thousands of CRS's. Relatively few
specify latitude/longitude.
Carl
>> Ivan,
>>
>> Re-using the URIs is a pretty good idea. However, there are
>> a couple of
>> advantages to the current approach:
>> 1. Abstraction: You can use "wgs84" to represent both the 2D and 3D
>> CRSes, depending on whether altitude is present
>> 2. Brevity
>
> In my opinion, the URI is a good idea, because it removes the need for a
> registry. *However*, just because the CRS is defined in the urn space
> does not necessarily mean that the corresponding definition is good
> enough for the geo URI, because as you see from the draft, there's more
> needed to have the URI semantics defined, even if the CRS is clear:
>
> - What is the meaning of the "x","y","z" coordinate component
> - What are valid URIs
> - How does comparison work
> - Are there any security considerations
>
> So there definitely needs to be documentation for how each CRS to be
> used in the geo URI is to be mapped (note that there are many many CRSes
> that don't use the longitude/latitude scheme, for a start - also many
> CRSes have completely different definitions of the third dimension).
>
> So, just adding the CRS to the URI parameter is not good enough for a
> full definition - which means that we need a document for new CRSes
> anyway.
>
> Which, in turn, removes the advantage of not needing a registry...
>
> BUT - i think it is definitely a good idea to align the "identifier
> string" that ogc uses and what is the token in the "crs" URI parameter
> (i think we are fine with "wgs84").
>
> BTW, i have tried to locate that URN registry - could you provide me
> with a pointer?
>
> Alex
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