Nice to see this here! I'm Sanjay Bhangar - I recently gave a talk about some of the history of the project and the technical architecture / setup at State of the Map, US (talk should be online soon).

This is essentially a long-running experiment in repurposing the OpenStreetMap software and architecture to map historical objects, with some modifications to handle dates: essentially, we generate vector tiles for the data and then use client-side filtering of the vector tiles to enable the time slider you see on the site.

Recently, we've been getting quite a lot of usage, and some folks mapping some areas really deeply, which is fantastic to see - of course, it all throws up very interesting questions, some of which are going to be harder to solve than others: we use OpenStreetMap's free tagging system, so a lot of these things would have to evolve as community consensus on tag usage, as OSM has.

As @nfgusedautopart says, it really is a big experiment .. all our code and discussions are open of course, and would love for you to contribute / jump in. This is the Github org: https://github.com/OpenHistoricalMap/

Fork of openstreetmap-website code-base: https://github.com/OpenHistoricalMap/ohm-website

Code for our deploy process to deploy the website code as well as associated services like Overpass (query tool), Tasking Manager (tasking tool), etc: https://github.com/OpenHistoricalMap/ohm-deploy/ (uses Helm + Kubernetes for the deploy).

Consolidated issues: https://github.com/OpenHistoricalMap/issues/issues

There's definitely some wild, fun problems in there - dealing with fuzzy dates, disputed historical facts, events .. though my favourite is likely the coastline problem: https://github.com/OpenHistoricalMap/issues/issues/329

Thanks for posting this here, and super happy to answer any questions if I'm able to.

Great concept! Looks like the main focus for now was US and German states and territories, which probably is a good proving ground for the general system. One thing you'll have to contend with, that those two mostly won't be test cases for, is the historical fact that lots of historical territories have fuzzy borders, either because we don't now know what the borders were, or because they were sort of amorphous even at the time. Early US states and territories "solved" this problem by drawing arbitrary nonsense lines on a piece of paper, and your map faithfully reflects that, but the trick won't work for a lot of others.

open problem. this is a very public experiment. participation and input are welcome.

Interesting.

See also https://davidrumsey.georeferencer.com/

Rumsey has a lot of interesting maps. i reference their collection from time to time. but a lot of maps (see the NY State Archive and Library of Congress, among others) are not georeferenced. there are various tools for dealing with this; i mostly use mapwarper.net

I love this!

Will it be possible to plot historical events on the map? I'd love to see e.g. a month-by-month combined timeline+map of Napoleon's invasion of Russia, or the D-Day invasion.

It would also be neat to be able to link a series of historical events into a sort of "guided tour", to make the events discoverable and put them in context.

Events are an open discussion topic. right now i personally am trying to figure out event modelling for the Battle of Antietam (Sept 1862) as there is good data available. in the long term, likely we'll want to have a parallel database to contain event data. we're still working through this.

I don't think should be encoded in the map, but imagine if Wikipedia facts were encoded with time + coordinates, then a mashup could illustrate them on a map like this

Wikidata does that: https://www.wikidata.org/wiki/Q151018

That is an interesting project. I wonder how they handle history that is disputed between countries. The Balkan peninsula would be quite spicy to map out historically :)

we haven't worked that out yet. i think we would probably design something that documented the disputes. yet another thing to put on the list.

perhaps borders can be documented with a "claims" attribute, so that in the case they are disputed, the different claims are shown at the same time

it would likely be some variation on that. the precise scheme to be used would need to be worked out, and i'd argue we should probably consider a variety of historical disputed border situations to make sure we cover the possibilities.

The first think I noticed was this "OHM Worldwide Rendering Testbed" about 30 miles east of Seattle. https://openhistoricalmap.org/#map=12/47.7505/-121.7306&laye...

natfoot set that up as i recall. the rendering engine is relatively new and we're still working through how we want certain aspects of it to work. this is all kind of a big experiment where we're standing in the middle of a field with our pants down around our ankles.

Funny! Right in my back yard

This is an amazing idea.

Though I wish they had seeded the map with OSM data so people can work backwards. Even when I look at 2022, Barcelona is bare except a few major roads.

Edit: Ah it seems to be based on OSM, but still something is going wrong with the current date I think, as I should see the whole city then.

Hello! I’m one of the folks working on OHM. We use the OSM technology stack with some modification, but we don’t import all of OSM due to data license issues.

pre-importing OSM data could be counter productive. OSM data is not generally populated with start_date tags, most mappers are not concerned with this issue. the result would be that all of the modern map (with rare exceptions) would project back through history irrespective of the actual start date. the result would be a staggering task to make OHM useful.

i've been posting replies without saying who i am. i am a member of the OHM advisory board as well as 10 year+ participant in OHM, Richard Welty.

I think some work should be put on the slider. The fast forward mode goes from decade to decade instead of just going from year to year faster. Also the site can't keep up with the accelerated speed so you miss tons of changes

an improved version of the slider is in the works.

Interestingly Belgium and the Netherlands are missing in year say 1900.