Empfohlen
Weitere ähnliche Inhalte
Ähnlich wie The State of Time in OpenHistoricalMap
Ähnlich wie The State of Time in OpenHistoricalMap (13)
Kürzlich hochgeladen
Kürzlich hochgeladen (20)
The State of Time in OpenHistoricalMap
- 1. The State of Time in OHM • Currently using the formats described on the OSM start_date page • And of course we support end_date • Date granularity is not limited by the database • Should be able to use any timestamp in ISO 8601 extended format • (don’t use basic format and expect it to work, not that anyone is likely to do that) • Note that ISO 8601 is a little bit of a can of worms
- 2. The State of Time in OHM • About 2 years ago we got the new Vector Rendering engine with the time slider • year by year granularity • improved version now • a move to day-by-day granularity is in the offing with a much more capable time slider • Note that the DB should be treated as a Database of facts, including dates and times which are as precise as can be documented
- 4. Uncertainty and Imprecision • Frequently we cannot precisely nail down start and end dates • Maps and aerial photos mostly provide “point in time” dates • Document what we know • Currently we are using OSM start_date formats • OSM refers to ISO 8601 but then defines an additional ad-hoc set of notations for intervals, imprecision and uncertainty • ISO 8601 has since been extended with its own notations for the same
- 5. Uncertainty and Imprecision • Library of Congress EDTF (Extended Date Time Format) • An official profile of ISO 8601-01 and 8601-02 • newer than most of the date formatting discussion on the start_date page • EDTF is a well defined, open and publicly available standard • https://www.loc.gov/standards/datetime/
- 6. Alternate Formats • There has been some discussion of other formats that should be supported • Other International, such as various Asia-Pacific date schemes • Julian and Roman • likely solution is a prefix with a :, when absent Gregorian is assumed • Julian and Gregorian overlap • The changeover took centuries • Roman (pre Julian reforms) will require lookup tables, there is no formula
- 7. EDTF not supported • Not officially adapted yet, although leaning that way • Temporary hack • put a supported time, possibly incomplete, in start & end date • use start_date_edtf and end_date_edtf to contain a well formed EDTF date specification
- 8. Quick EDTF Tour • Intervals • 2022-03-31/2022-04-02 • Precision • 201X • 2010-03-1X
- 9. Quick EDTF Tour • Uncertainty • 2010? (may be 2010 but uncertain) • 2010~ (approximate) • 2010% (both uncertain and approximate)
- 10. Quick EDTF Tour • More Intervals • 2010/.. (open ended) • ../2010 • 2010/ (unknown end of interval)
- 11. EDTF and start_date (or end_date) • start_date_edtf=2010/2012 • start date is 2010, 2011, or 2012 • start_date_edtf=2010/.. • earliest possible start date is 2010