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Life Cycle Modeling in OpenHistoricalMap

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Life Cycle Modeling in OpenHistoricalMap

  1. 1. Life Cycle modeling in OpenHistoricalMap Richard Welty, SOTM US 2022
  2. 2. Life Cycle Modeling in OHM • Substantially more complex than anything anyone is trying in OpenStreetMap • Proposals have been made for OSM but not gone anywhere • limited motivation given OSM focus on Now • after all, we have an OHM for that
  3. 3. Time in OHM • integral to Life Cycle • but I’ll talk about it in a lightning talk tomorrow(?) • assume we’re using something related to ISO 8601-01 and -02 • potential for historic and/or non-ISO times in the future • we are focused on the times in tags, not internal to the vector renderer
  4. 4. Life Cycle mapping brings complexity • Not any way to avoid complexity • We have to decide, then, how we will represent and deal with it • Complexity impacts both mappers and data consumers • easy for one may not be easy for the other
  5. 5. Ground Rules • OpenHistoricalMap uses OSM data schema • nodes, ways, relations, tags • tagging is broadly compatible
  6. 6. Common OSM Life Cycle • fine for what OSM uses it for • OSM also has things like the disused namespace • all built around the idea of *now* • Does not handle OHM levels of complexity highway=construction construction=primary
  7. 7. Alternate Approaches: Duplicate Geometry • Can be challenging to edit with current tools • Can be challenging to even spot with current tools • Potential to be made easier with well conceived extensions and/or plugins • Sometimes unavoidable in contexts with dense histories
  8. 8. Alternate Approach: Lifecycle Encoding in the key • abandoned OSM proposal • embed date information in key side of key/value pair name:2005-2010=My Name • could generalize to any key value
  9. 9. Alternate Approach: Lifecycle Encoding in the key • Issues • hard to search via overpass or other means • stress on data consumer side • compatibility issues with both start_date specs and with ISO 8601/EDTF • database people don’t like stashing data on the key side of a KV pair
  10. 10. Alternate Approach: Life Cycle with Relations • Failed OSM proposal • Treat life cycle data as metadata to be decoupled from geometry • Carry start_date and end_date in relations • Being actively experimented with in OHM
  11. 11. Alternate Approach: Life Cycle with Relations • Cannot eliminate complexity - but we can move it • Instead of sorting through a thicket of complex keys, traverse a graph of relations, ways, nodes • We may not need a new relation type - we can add start_date and end_date to any existing relation type • There maybe other reasons for a generic “group” relation type
  12. 12. First Experiment - Ghost Tracks
  13. 13. First Experiment - Ghost Tracks • uses abandoned proposal for “circuit” relation type (abandoned, but in use) • same in OSM and OHM (except OHM adds end_date) • leaflet widget treats data returned by overpass the same for OSM & OHM • NOTE: the OHM rendering engine is *not* the only data consumer and it is not the only viable view of OHM data
  14. 14. New Experiments • “Life Cycle Laboratory” • try extending these concepts to other kinds of entities? • Easy start by adding start_date and end_date to existing OSM relation types • OHM rendering engine support is evolving, some works and some doesn’t • Useful for figuring out things to ask for
  15. 15. NYS Canal System • Uses waterway tagging (relations & ways) • Relation complexity increases substantially with size and complexity over time • Erie Canal was substantially improved between 1837 and 1862 • changed from year to year • Need to consider better tool support • https://www.openhistoricalmap.org/#map=15/42.7818/- 73.7050&layers=O&date=1900&daterange=1783,1900
  16. 16. Life Cycle Visualization
  17. 17. Life Cycle Visualization
  18. 18. Events? • Potential to model historical events • Voyages • Military battles & campaigns • Same DB or a parallel DB? • I’m experimenting in the existing OHM DB for now

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