[Geojson] Interpretation of "extra" coordinate dimensions
Evan James Bowling
bowlin10 at msu.edu
Wed Aug 31 10:18:10 PDT 2011
I am a user of the spec *(not an author)*, have good experience with web
the spec. My thoughts are as follows:
1. The GeoJSON spec should specifically forbid any dimensions beyond XYZM
until enough practical applications can be brought up to merit the
2. JSON in general is used for transferring small-medium datasets. Locking
down the spec on this detail can help data sets to remain readable as well
3. All of the uses of GeoJSON I have come across would be functional with
the limited amount of dimensions.
4. Perhaps a more general spec can be laid out for representing more types
of spatial information, and GeoJSON would be a more restricted version using
similar property names. There are certainly a lot of new web applications
that could benefit from a shared base data structure such as games, music
notation (vexflow), white boarding tools, and mind maps.
Thanks for bringing this up Daniel!
On Wed, Aug 31, 2011 at 12:03 PM, Daniel Azuma <dazuma at alumni.caltech.edu>wrote:
> Hi everyone,
> Just joined the list, so a quick intro: My name is Daniel Azuma. I wrote
> and maintain a GeoJSON builder/parser for Ruby called rgeo-geojson. (
> http://virtuoso.rubyforge.org/rgeo-geojson/) It parses GeoJSON into
> objects built by RGeo, which is a Ruby implementation of the OGC SF spec.
> Right now my parser ignores and throws away any "extra" dimensions beyond
> XYZ(M), because the SF spec (and hence RGeo) doesn't have any notion of
> dimensions beyond XYZM. However, I notice that the GeoJSON spec does allow
> for any number of dimensions in a coordinate. I wanted to ask what is
> generally expected of parsers when dealing with such "extra" dimensions,
> whether they should be considered meaningful.
> I ask because I have a user who wants to use extra dimensions to store
> metadata associated with point coordinates. That is, he wants to do this:
> "type": "Point",
> "coordinates": [102.0, 0.0, 0.0, "2011-03-29T08:38:50Z", 3.54, 39.80]
> where the coordinates are X, Y, Z, timestamp, speed, bearing. I responded
> to him that I thought such metadata should be represented as properties in a
> Feature object, but he prefers conciseness over expressiveness in his use
> case. So I was wondering about the intent of allowing arbitrary extra
> dimensions in a coordinate, and whether, in the opinion of the authors of
> the spec, this was a case that GeoJSON parsers do (or should) handle.
> Daniel Azuma
> Geojson mailing list
> Geojson at lists.geojson.org
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