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Hi Jukka,<br>
<br>
On 30/03/15 09:46, Jukka Rahkonen wrote:<br>
<span style="white-space: pre;">> Homme Zwaagstra <hrz
<at> geodata.soton.ac.uk> writes:<br>
><br>
>><br>
>><br>
>> <br>
>> P.S. on the proposal below, perhaps things could be
'standardised'<br>
>> even more by<br>
>> including the cornerCoordinates in both wgs84 and
native coordinate<br>
>> systems<br>
>> (much like gdalinfo does at the moment). In this way
you can be<br>
>> guaranteed of<br>
>> getting geojson output in its default coordinate
system. e.g.:<br>
>> { "cornerCoordinates":<br>
>> { "wgs84": ... GeoJSON FeatureCollection
transformed to EPSG:4326<br>
>> ...,<br>
>> "native: ... GeoJSON FeatureCollection in native
coordinates ...<br>
>> }<br>
>> }<br>
>> Best regards,<br>
>> Homme <br>
><br>
><br>
> Hi,<br>
><br>
> Do you want to open this can of worms? Hardcore GeoJSON folks
will tell that<br>
> "GeoJSON FeatureCollection in native coordinates" does not
exist because<br>
> newest GeoJSON draft wants to support only one CRS which is
WGS84<br>
> Longitude-Latitude. From<br>
>
<a class="moz-txt-link-freetext" href="https://datatracker.ietf.org/doc/draft-butler-geojson/?include_text=1">https://datatracker.ietf.org/doc/draft-butler-geojson/?include_text=1</a><br>
><br>
> "Other coordinate reference systems, including ones described
by CRS<br>
> objects of the kind defined in [GJ2008] are NOT RECOMMENDED."<br>
><br>
> And then hardcore OGC standard folks will tell that the axis
order of<br>
> coordinates must follow the official EPSG:definitions.<br>
><br>
> At least for me as a user of ogrinfo and gdalinfo the bounds
in the native<br>
> units are the ones which I need. A few times in a year the
geographic bounds<br>
> may be useful but I have not even thought before writing this
mail that<br>
> ogrinfo does not report the WGS84 bounds while gdalinfo does.
I deal also<br>
> often with data with unknown CRS like shapefiles without .prj
and tiff+tfw<br>
> files. I suppose that bounds of those cannot be expressed as
GeoJSON<br>
> FeatureCollections according to the new draft because nobody
knows how to<br>
> re-project from unknown to WGS84 and back..</span><br>
<br>
The fact that it is a can of worms is what made me think that
providing both<br>
options would be helpful from a practical point of view: many tools
expect<br>
geojson to be in wgs84 (in which case use the transformed object)
but equally as<br>
in your use case it is important to be able to access the native
coordinates.<br>
<br>
I think the key point I wanted to make is that having the
coordinates in geojson<br>
format makes them more generally accessible, whatever the CRS, but
if there is<br>
also the option to meet wider (geojson) expectations by also having
them in<br>
wgs84 then that can be no bad thing.<br>
<br>
Because the JSON output is quite high level it would be nice to not
to have to<br>
add additional steps such as coordinate transformations to make more
general use<br>
of the data. E.g. it would be nice to just be able to pull out the
extent of a<br>
raster and have it available in a 'known' usable format, such as
adding it as a<br>
GIS layer, database extent etc.<br>
<br>
<span style="white-space: pre;">><br>
><br>
> I think that the original RFC keeps things simple by relying
on plain XML<br>
> and JSON and not mixing GML and GeoJSON into the play.
However, I am not a<br>
> programmer so I may be all wrong.</span><br>
<br>
The geojson and xml is designed to be ingested by programs: I'm in
favour of<br>
making this process as easy as possible using standard tools and
formats.<br>
<br>
I didn't mention GML (the XML component doesn't interest me as much)
but now<br>
that you have... ;)<br>
<br>
Best regards,<br>
<br>
Homme<br>
<br>
<span style="white-space: pre;">><br>
><br>
> -Jukka Rahkonen-<br>
><br>
><br>
><br>
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<br>
<br>
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