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Type of site | Collaborative mapping |
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| Available in |
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| Owner | Community-owned; supported by OpenStreetMap U.S.[2] |
| Products | Geographic data |
| URL | www |
| Commercial | No |
| Registration | Required for contributors, not required for viewing |
| Launched | 2013; 12 years ago (2013)[3] |
| Current status | Active |
Content license | Various |
OpenHistoricalMap (also spelledOpen Historical Map and abbreviatedOHM) is an onlinecollaborative mapping project developing ahistorical map of the world usingOpenStreetMap technology and processes.[4][5][6] Whereas OpenStreetMap only includes data about the present day and deletes data as it becomes outdated, OpenHistoricalMap welcomes historical data and preserves multiple copies of a feature as it changes over time.[7][8] The OpenStreetMap community views OpenHistoricalMap as an outlet for keeping outdated names out of OpenStreetMap, where they could cause misunderstanding.[9]
Thedomain name OpenHistoricalMap.org was purchased in 2009[10] and in 2013 started an initial fork of theOpenStreetMap website software there.[3][11]
The similarly namedOpenHistoryMap project started in 2015 to share archaeological and historical data with anopen access model. However, it has apeer review process,[12] which is distinct from the OpenHistoricalMap and OpenStreetMap projects' focus on freevolunteered geographic information.[4]
In 2016, OpenHistoricalMap suffered ahard disk drive failure but managed to recover most data from a contributor's backup.[11] Since 2017,Oakland, California–based GreenInfo Network andWashington, D.C.–based Development Seed have developed and maintained the project's technical infrastructure.[13][14] In 2018, longtime host Topomancy shut down and transferred ownership of the OpenHistoricalMap domain to the Wikiwar Heritage Council.[15]
In 2020, OpenHistoricalMap introduced a "timeslider" that allows users to interactively filter map data by time period. This feature is credited with spurring the project's growth.[4] In May 2021, OpenHistoricalMap became a charter project of OpenStreetMap U.S., a nonprofit local chapter of theOpenStreetMap Foundation.[2]
OpenHistoricalMap allows anyone with a free account to contribute directly to the map through an editor such as theiD Web application or theJOSM desktop application. Contributors can georeference out-of-copyright maps and trace features from them.[16] They can contribute data individually or as part of guidedmapathons.[17]
The software that powers the OpenHistoricalMap website is maintained onGitHub as a collection of open-source projects. Many of these projects, such as the iD editor, areforks ofOpenStreetMap software projects that have been adapted to a data model with a time dimension.[14]
The OpenHistoricalMap community has organized projects to map certain historical periods and themes in detail. Major contributions have included:
Individual mappers have also contributed data on thegentrification in theCheonggyecheon andDongdaemun areas ofSeoul[23] and former infrastructure related toErie Canal andHarmony Mills in New York.[24] Mappers georeference old maps on platforms such as OldInsuranceMaps.net in order to complete the basemap.[25]
OpenHistoricalMap focuses on historical objects but does not collect data on historical events per se.[26]
OpenHistoricalMap has a data model largely identical tothat of OpenStreetMap, including the consolidation of all data into a single layer.[26] However, OpenHistoricalMap's addition of a time dimension makes the data more complex.[27] The tags for indicating a feature's start and end dates are much more important. There are multiple approaches to representing a real-world place or object that changes over time. It can be represented by multiple features in the database, each corresponding to different start and end dates. Alternatively, individual tags can be qualified by start and end dates, and more complex approaches involving relations have been proposed. Dates are formatted according toISO 8601 orEDTF.[24]
The OpenHistoricalMap project started from scratch with an empty database.[4] As of October 2021, OpenHistoricalMap's coverage was characterized as "very sparse" with few buildings mapped.[28] As of 2024, atriplestore representation of OpenHistoricalMap was comparable in size to an extract of OpenStreetMap data inFinland but had many more points than polygons, and of the polygons, many were similarly shaped.[29] OpenHistoricalMap's coverage includes multiple copies of an object as it changes over time.[7]
On the main project website, a map consisting ofvector tiles visualizes the historical data interactively in several styles, including a functional Historical style and an artistic Woodblock style. Aslider allows visitors to filter the map data to a point in time from 4001 BCE in theproleptic Gregorian calendar to the present day.[30] When a feature is selected, content fromWikipedia andWikimedia Commons is displayed in a sidebar based on the tagged Wikipedia article title orWikidata item identifier. A custom instance of theNominatim search engine returns search results across time periods.[14]
OpenHistoricalMap data is available for reuse in other projects. In addition to theREST API, a weeklydatabase dump allows bulk downloads inProtocol Buffers–encoded OSM XML format. There is also an instance of theOverpass API for structured querying of the data across time periods. These tools are configured and deployed as part of the reusable osm-seed package.[11]
Ecologists have used OpenHistoricalMap data to track the change of geological features over time such as the path of rivers.[31]Gramps Web uses an OpenHistoricalMap basemap to place genealogical data in a historical context.[32]
Individual features within the OpenHistoricalMap database are licensed independently. The project prefers that new contributions be dedicated to the public domain through aCC0 dedication.[33] However, a fraction of tagged elements have been contributed under other licenses, most commonly theOpen Database License (used by OpenStreetMap) andCreative Commons Attribution-ShareAlike.[34]
The software that powers the OpenHistoricalMap website is available under theGNU General Public License.[35]
{{cite web}}: CS1 maint: bot: original URL status unknown (link)Two examples of OSM applications that focus on historical data sets are HistOSM1 and OpenHistorical ... OpenHistoricalMap is an effort to use the OSM infrastructure as a foundation for creating a universal, detailed, and historical map of the world.
OHM is a fork of OpenStreetMap where contributors map historical features.
{{cite web}}: CS1 maint: bot: original URL status unknown (link)
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