[GeoJSON] Fwd: [Geojson] I-D Action: draft-ietf-geojson-04.txt

[Jukka Rahkonen]

Martin Daly kirjoitti 2016-06-23 22:45:
>> It looks that with this version the use of any other CRS than CRS:84 
>> is denied. If
>> there still happens to be users who prefer some other CRS for example 
>> because
>> round-trip from the native CRS used in the database into
>> CRS:84 and back may change the cooordinates, should they start calling 
>> such
>> geospatial JSON with some other name than GeoJSON?
> 
> 4. CRS says:
> 
> "Note: the use of alternative coordinate reference systems was
>    specified in [GJ2008], but has been removed from this version of the
>    specification because the use of different coordinate reference
>    systems -- especially in the manner specified in [GJ2008] -- has
>    proven to have interoperability issues.  In general, GeoJSON
>    processing software is not expected to have access to coordinate
>    reference systems databases or to have network access to coordinate
>    reference system transformation parameters.  However, where all
>    involved parties have a prior arrangement, alternative coordinate
>    reference systems can be used without risk of data being
>    misinterpreted."
> 
> The last sentence should cover your use case.

I wonder how to to make such a prior arrangement with all involved 
parties if one part is software like GDAL, MapServer, or GeoServer, and 
the other part is any user of such software or service. Would it make 
invalid GeoJSON if we just ocntinue to use the "crs" member of [GJ2008] 
and mention it in the documentation? Have you ever thought about making 
a new GeoJSON v 2.0 instead, or introducing sub-types or profiles like 
"crs_profile=strict", "crs_profile=GJ2008", "crs_profile=vendor"?

I have never met interoperability issues with the GJ2008 crs system 
myself but I believe that such have been occurred. I also believe that 
dropping crs altogether will lead to more interoperability issues in the 
future but I hope I am wrong.

BTW, if data is edited in a native crs that is not CRS:84/EPSG:4326, 
doesn't having the crs member make it possible for software to work 
without having access to coordinate reference systems databases or to 
have network access to coordinate reference system transformation 
parameters because they do not need to make transformation from CRS:84 
into the native system?


-Jukka Rahkonen-



> Martin