Re: [Geojson] Requests for comments on GeoJSON Events draft

[Matthias Müller <[e-mail]>]

Hi Sean,

 

Three comments / questions:

 

1) Are (time) intervals end-inclusive or end-exclusive? There are different policies around and this topic is excluded by RFC 3339. The definition also affects topological relations (e.g. adjacency tests between two or more intervals, containment tests between intervals and points).

 

End-inclusive examples:

2017-01-04T23:02:00 / 2017-01-04T23:03:00 -> includes the 2017-01-04T23:03:00 instant

2017-01-04T23:02:00 / 2017-01-04T23:03:59.999 -> excludes the 2017-01-04T23:03:00 instant

2017-01-04 / 2017-01-06 -> includes 2017-01-06

 

End-exclusive examples:

2017-01-04T23:02:00 / 2017-01-04T23:03:00 -> excludes the 2017-01-04T23:03:00 instant

2017-01-04 / 2017-01-06 -> excludes 2017-01-06

 

Pro/Con: Seems that end-inclusive is more intuitive for dates, while end-exclusive is more intuitive for time There’s no policy that is great for both cases.

 

 

2) [editorial]: “As with instants, the values of "start" and "stop" are RFC 3339 date/time strings.” -> “stop” should be “end”.

 

3) Does the spec permit truncated / imprecise time stamps, such as “2006” or “2006-12-01T12:00”?

 

 

 

Matthias

 

 

From: GeoJSON [mailto:[e-mail]] On Behalf Of Sean Gillies
Sent: Wednesday, January 04, 2017 10:33 AM
To: [e-mail]
Subject: [Geojson] Requests for comments on GeoJSON Events draft

 

Hi and Bonne Année all,

With help from many of you, I've been working on a GeoJSON extension for event-like features

     <https://github.com/sgillies/geojson-events> https://github.com/sgillies/geojson-events

and have drafted a spec:


     <https://sgillies.github.io/geojson-events/draft-gillies-geojson-events.html> https://sgillies.github.io/geojson-events/draft-gillies-geojson-events.html
     <https://sgillies.github.io/geojson-events/> https://sgillies.github.io/geojson-events/

It's pared down dramatically from what we discussed in the past. Fuzzy time periods are out and so are temporal bounding boxes because the use cases for these are rare. GeoJSON has been doing well so far without any representation of fuzzy geometry and I think the situation is about the same for time.

I received an suggestion to consider ISO 8601 style time intervals. This would allow a single string value to represent an instant or interval,

    "when": "2017-01-04/2017-01-05"

 

instead of 

    "when": {"start": "2017-01-04", "stop": "2017-01-05"}

but this seems harder to use because support for it in parsers is rare.

I was asked about recurring intervals like "every other Friday," but I think this isn't necessary. GeoJSON doesn't have a concept of non-literal geometries either.

Some time ago we arrived at rough consensus that "moving objects" and "event-like features" are either different things or very different models of the same things. Moving objects are not specified in my draft.

 

I have two objectives for this draft:

* To establish a common representation for time in GeoJSON that mappers of events, whether they are scientists or journalists or historians, can share.

* To set an example for other extension projects.

I'd love comments on how it can be improved to better meet those objectives. Thanks!

-- 

Sean Gillies