Presentation about OpenHistoricalMap for OSM US Mappy Hour, July 2020

1. Richard Welty
Mappy Hour - 2020-07-08
Open Historical Map

2. The Goal
… is to create the world's most
universal, detailed, and out-of-date
map

3. The Reality
• There is much blank space in OHM
• There is more than enough of history after all
• There are some very detailed areas

4. Projects
https://wiki.openstreetmap.org/wiki/Open_Historical_Map/Projects

5. Projects

6. What’s the same as OSM?
• The database schema
• Editing API
• The editors
• Fork of iD on the Open Historical Map website
• Easy to con
fi
gure JOSM to access OHM instead of OSM
• Our own instance of Overpass, unmodi
fi
ed
• OSM tagging largely relevant

7. What’s Different?
• Mapping things that no longer exist is encouraged
• Mixed licensing model (license tag)
• CC0 encouraged
• CC-BY-SA is ok
• mass copying from OSM is a bad idea because of the way ODbL works
• start_date and end_date tagging is important
• Care with sourcing - we are acting as Public Historians
• Documentation of active projects in the Wiki is encouraged

8. What’s Different?
• Vector tiles with the Time Slider
• new with the recent reconstruction of the site
• Time Slider uses start_date and end_date to determine what to display
• start_date & end_date
• currently ISO date formats supported (yyyy-mm-dd)
• will be extensions in the future

9. Timeslider demo

10. Editing
• When all of history is in front of you in a map editor, information density can
become insane, or at least a bit unwieldy
• JOSM
fi
lters o
ff
er some help
• compare start & end dates to particular years
• iD may have
fi
lter support coming to help
• not ideal in current form, but usable

11. Tagging Experimentation
• no equivalent to OSM tagging list and tag voting
• we are on a learning curve with respect to historical tagging
• currently working with relations as ways to show di
ff
erent con
fi
gurations over
time
• use of street relation proposal or associatedStreet relation as ways of
grouping ways in to streets that may have changed name, paving condition,
classi
fi
cation, or status over time
• use multipolygon same way for areas that change over time

12. Sourcing
• modern sources (Bing, Mapbox, ESRI, etc.) of limited value
• permissions may not extend to OHM
• Mapbox and ESRI have responded positively to our requests
• most importantly, stu
ff
we want to map is often not in modern imagery
• historic sources are everywhere
• Libraries, Universities, Historical Societies, Museums
• May or may not be geo referenced
• mapwarper.net
• for maps and aerial imagery that is not available in georeferenced form (TMS, WMS, WTMS
URLs)

13. Sourcing Dates
• Easy to say “start_date” and “end_date”, harder to do
• maps and aerials o
ff
er point-in-time information
• use external written documentation where found
• build date ranges by referencing multiple sources
• in Albany, I’m looking at a wealth of maps at various points in time
• access your local historical community

14. OHM project mindset
• long and medium term projects
• can’t
fi
nish it quickly by looking at bing and maybe driving out for a ground
survey
• plan on gradual improvement as knowledge develops
• wikipedia can be a research start point - but probably never an end point
• follow and verify citations
• when you
fi
nd problems in wikipedia, you do actually have the power to
address them - if you’ve done the research

15. Examples - military history
• Munin project
• WWI
fi
eld forti
fi
cations
• American Civil War
• Gettysburg
• Antietam
• potential for driving animations

16. Examples
• Diversity
• Seneca Village (NYC)
• Rapp Road Historic District (Albany NY)
• Potential diversity projects
• Tulsa OK - Black Wall Street as it was
• other majority minority communities of note
• deed restrictions

18. Examples
• OHM-OSM synthesis
• Monument/Statues
• migrate monuments/statues to OHM as they are removed
• document start & end dates, other properties
• Ghost Tracks
• race tracks of the past

19. Online presence
• historic@openstreetmap.org mailing list
• OSM US Slack
• OSM Discord
• @OpenHistMap twitter
• OpenHistoryMap Facebook group
• #ohm on irc.oftc.net
• may be retiring irc channel