{"action":"closed","issue":{"url":"https://api.github.com/repos/mapbox/mapping/issues/120","labels_url":"https://api.github.com/repos/mapbox/mapping/issues/120/labels{/name}","comments_url":"https://api.github.com/repos/mapbox/mapping/issues/120/comments","events_url":"https://api.github.com/repos/mapbox/mapping/issues/120/events","html_url":"https://github.com/mapbox/mapping/issues/120","id":106324677,"number":120,"title":"Japan OSM improvement","user":{"login":"planemad","id":126868,"avatar_url":"https://avatars.githubusercontent.com/u/126868?v=3","gravatar_id":"","url":"https://api.github.com/users/planemad","html_url":"https://github.com/planemad","followers_url":"https://api.github.com/users/planemad/followers","following_url":"https://api.github.com/users/planemad/following{/other_user}","gists_url":"https://api.github.com/users/planemad/gists{/gist_id}","starred_url":"https://api.github.com/users/planemad/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/planemad/subscriptions","organizations_url":"https://api.github.com/users/planemad/orgs","repos_url":"https://api.github.com/users/planemad/repos","events_url":"https://api.github.com/users/planemad/events{/privacy}","received_events_url":"https://api.github.com/users/planemad/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/mapbox/mapping/labels/cleanup","name":"cleanup","color":"fbca04"}],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":63,"created_at":"2015-09-14T11:47:09Z","updated_at":"2015-10-27T12:14:27Z","closed_at":"2015-10-27T12:14:27Z","body":"Based on observations from #116. There are multiple data issues in japan which requires a comprehensive cleanup strategy with close involvement of the Japanese OSM community.\r\n\r\nThis ticket will track all the high level conversations and strategy on improving OSM data for Japan.\r\n\r\n**Existing data issues**\r\n- Most of Japan road network has been imported from [Yahoo Japan](https://wiki.openstreetmap.org/wiki/YahooJapanALPS_Data) in 2011\r\n- The road data has positional errors (5-30m) when compared to Strava GPS and includes incorrect topology that does not match satellite imagery. \r\n![screenshot 2015-09-14 16 08 10](https://cloud.githubusercontent.com/assets/126868/9848018/16328874-5afb-11e5-8fb4-a4eb52953b9a.png)\r\n- Roads in metropolitan areas have been realigned to the correct position, but large parts of the country are still untouched since 2011.\r\n![screenshot 2015-09-14 16 27 36](https://cloud.githubusercontent.com/assets/126868/9848298/8ec5afa8-5afd-11e5-9c7f-39b230ea85a1.png)\r\n- The Bing imagery coverage for Japan is comprehensive but does not match the OSM data or Strava GPS data. There is both an offset and orthorectification errors that varies throughout Japan.\r\n![](https://cloud.githubusercontent.com/assets/10141319/9680104/02624708-5312-11e5-85f5-b0f944405309.png)\r\n- There is high resolution orthorectified imagery for Japan from GSI which perfectly matches Strava GPS data and is the best imagery source available. The coverage of this imagery is not complete.\r\n![](https://cloud.githubusercontent.com/assets/126868/9682282/dccb1d38-5322-11e5-97c4-ab57ba45cf5e.png)\r\n\r\n**Data improvement strategy**\r\n\r\n1. Select project area\r\n   1. Priority: Urban areas > Highway corridors > Rural areas\r\n   2. Check the accuracy of orthorectified imagery and Bing imagery by comparing with GPS data. Publish offsets if required.\r\n   3. Evaluate extent of data offset and data freshness for the area\r\n   4. Publish findings and communicate with local mappers to initiate a mapping task\r\n2. Road realignment\r\n  1. Create a road improvement task using the [tasking manager](http://tasks.openstreetmap.in)\r\n  2. Verify imagery alignment using GPS data\r\n  3. For gridded networks, attempt to offset data to match imagery. If not successful delete imported unnamed roads and retrace area\r\n  4. Delete imported roads with no match to imagery\r\n  5. Realign all other roads and mark as finished\r\n3. Road tracing\r\n  1. Go through realigned tasks and invalidate to commence road tracing\r\n  2. Trace missing roads and tracks from imagery and mark as finished\r\n4. Validation\r\n\r\n**Next steps**\r\n- [x] Get feedback from Japan OSM community on above process\r\n- [x] @planemad to set up trial map improvement task: http://tasks.openstreetmap.in/project/38\r\n- [x] @planemad and @Rub21 to run task with team and closely monitor issues\r\n\r\ncc @mapbox/team-data "}}