[GeoJSON] Fwd: data series, time series in GeoJSON

[Matt Priour]

---------- Forwarded message ----------
From: "Matt Priour" <mpriour at kestrelcomputer.com>
Date: Sep 19, 2013 11:59 AM
Subject: Re: [GeoJSON] Fwd: data series, time series in GeoJSON
To: "Matt McClure" <matthewlmcclure at gmail.com>
Cc:

If you want extra dimensions in your crs then you should add them to the
end. If you prepend coordinates with time values, no existing geojson
parsers/readers are going to be able to properly represent those
coordinates. They will take the first value as x and second value as y and
may or may not do anything with 3rd or 4th coordinates.
On Sep 19, 2013 11:24 AM, "Matt McClure" <matthewlmcclure at gmail.com> wrote:

> Thanks, Tom. I hadn't found that conversation before.
>
> In that thread, Jerry Sievert came to the same LineString
> conclusion[1] that I did. And Sean Gilles countered that a collection
> of Points[2]. Enumerating each Point as JSON seems pretty verbose, but
> MultiPoint seems like a reasonable compromise that's not very
> different from LineString.
>
> Is there any precedent for using CRSs where the first two elements in
> a Position are not (easting, northing) or (latitude, longitude)? I'm
> unclear on whether the spec indicates that those MUST be the first two
> elements, or if a GeoJSON file MAY specify an alternative CRS that
> uses different kinds of values in the first two elements.
>
> [1]:
> http://lists.geojson.org/htdig.cgi/geojson-geojson.org/2013-August/000826.html
> [2]:
> http://lists.geojson.org/htdig.cgi/geojson-geojson.org/2013-August/000825.html
>
> On Thu, Sep 19, 2013 at 11:51 AM, Tom MacWright <tom at macwright.org> wrote:
> > There's a bit of a more recent conversation from last month[1] on the
> more
> > general case of 'values along a line', with a similar conclusion - it's
> not
> > an easy thing to implement for any general case and it's something that's
> > possible to do 'by convention' without a change to the standard.
> >
> > [1]:
> >
> http://lists.geojson.org/htdig.cgi/geojson-geojson.org/2013-August/000821.html
> >
> >
> > On Thu, Sep 19, 2013 at 11:48 AM, Matt McClure <
> matthewlmcclure at gmail.com>
> > wrote:
> >>
> >> Hi,
> >>
> >> I'm reading the GeoJSON spec as I'm working on a way to represent time
> >> series data. I've looked through the mailing list archives and I've
> >> found a conversation from October[1] and November 2011[2], and a
> >> rejected proposal on the wiki.[3]
> >>
> >> Does section 3[4] allow arbitrary CRS values, or does the condition
> >> that "" disqualify all CRSs that would use dimensions other than one
> >> of the two examples in section 2.1.1.[5]?
> >>
> >> I wonder if a time series representation would conform to the existing
> >> GeoJSON 1.0 spec using an alternative CRS. For example, using URNs as
> >> described in "Definition identifier URNs in OGC namespace"[6], I might
> >> construct a compound CRS and use it as follows:
> >>
> >>     {
> >>       "crs": {
> >>         "type": "name",
> >>         "properties": {
> >>           "name":
> >>
> >>
> "urn:ogc:def:crs,dataType:OGC:1.1:time,crs:OGC:1.3:CRS84,verticalDatumType:OGC:1.0:geoidal"
> >>         }
> >>       },
> >>       "type": "LineString",
> >>       "coordinates": [
> >>         [<time>, <lat>, <lng>, <alt>], [...], ...,
> >>       ]
> >>     }
> >>
> >> Would an example like this conform to GeoJSON 1.0?
> >>
> >> Best,
> >> Matt
> >>
> >> [1]:
> >>
> http://lists.geojson.org/htdig.cgi/geojson-geojson.org/2011-October/000597.html
> >> [2]:
> >>
> http://lists.geojson.org/htdig.cgi/geojson-geojson.org/2011-November/000601.html
> >> [3]:
> https://github.com/GeoJSONWG/geojson-spec/wiki/Data-Series-Proposal
> >> [4]:
> >>
> http://www.geojson.org/geojson-spec.html#coordinate-reference-system-objects
> >> [5]: http://www.geojson.org/geojson-spec.html#positions
> >> [6]: http://portal.opengeospatial.org/files/?artifact_id=24045
> >>
> >>
> >> --
> >> Matt McClure
> >> http://matthewlmcclure.com
> >> http://www.mapmyfitness.com/profile/matthewlmcclure
> >> _______________________________________________
> >> GeoJSON mailing list
> >> GeoJSON at lists.geojson.org
> >> http://lists.geojson.org/listinfo.cgi/geojson-geojson.org
> >
> >
> >
> > _______________________________________________
> > GeoJSON mailing list
> > GeoJSON at lists.geojson.org
> > http://lists.geojson.org/listinfo.cgi/geojson-geojson.org
> >
>
>
>
> --
> Matt McClure
> http://matthewlmcclure.com
> http://www.mapmyfitness.com/profile/matthewlmcclure
> _______________________________________________
> GeoJSON mailing list
> GeoJSON at lists.geojson.org
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>
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