[GeoJSON] Values along a line in GeoJSON

[Sean Gillies]

Hi Tom,

This sounds a little bit like the Data Series Proposal we didn't accept 2
years ago.

  https://github.com/GeoJSONWG/geojson-spec/wiki/Data-Series-Proposal

Could you model a GPX track as a collection of points and then add a
constraint to the collection, that the points are ordered in time and that
the ordering must be understood by processors?

Not to get all "philosophy in a time of GIS formats," but the path
comprising all the points is a weird kind of feature, not something that
exists as a whole at any one time except possibly the final time. It feels
more like a collection of points to me than a single geometric object.


On Thu, Aug 8, 2013 at 8:34 AM, Tom MacWright <tom at macwright.org> wrote:

> Hey all,
>
> So recently I've been working on a site that centers around editing maps
> and treats GeoJSON as its latin[1]. As one of the features on this site, it
> uses a library to convert from other formats - KML, CSV, and GPX - to
> GeoJSON[2]. This has been pretty great, and clearly GeoJSON is a superset
> of CSV, and can handle most bits of KML. That said, though, GPX files
> present a bit of an issue.
>
> That is, GPX allows you to specify values at points - a segment is made up
> of trackpoints, which can have their own data points - elevation, time,
> heart rate, and so on. The conversion library right now simply converts
> segments into lines and throws away data-at-points.
>
> So, my question is: what's a better way? I don't want to encourage or
> imply that GeoJSON should grow, since its simplicity is incredibly
> valuable. But, in order to stem the fidelity loss in this conversion, is
> there a good pattern for storing this kind of data? What kind of data is
> this - what's the right term for values-on-lines and is it weird that GPX
> supports it while other geospatial formats don't?
>
> Thanks for any knowledge or advice here, it's much appreciated!
>
> Tom
>
> [1]: http://geojson.io/
> [2]: https://github.com/tmcw/togeojson
> [3]: http://en.wikipedia.org/wiki/GPS_eXchange_Format#Sample_GPX_document
>
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>


-- 
Sean Gillies
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