Greenville SC City Address and Building footprint import

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Greenville SC City Address and Building footprint import

Background

See also: Greenville_City_GIS_Import

GIS data has been received from the city GIS office with permission to use in OSM. There are about 44,800 addresses to be added to OSM and about 17,000 buildings as a candidate for building footprint geometry replacement.

Type of license: Public domain, and also an email has been obtained from the GIS office granting permission for OpenStreetMap to use the data.

Goals

  • Match and attach address points to new buildings
  • Match and attach address points to existing buildings in OSM that have no or incomplete address data
  • Upload remaining address points
  • Improve certain existing building footprints in OSM using higher quality footprints from the new dataset. This step is performed by the merge program using a "replace geometry" algorithm to preserve history and reuse existing nodes. Buildings created from pre-Bing imagery are also candidates for geometry replacement.
  • Validate against existing data before upload (house on waterway or highway)

Accounts

Data Merge Workflow

Conversion scripts / program are at https://github.com/OpenStreetMapSC/GreenvilleCityData and https://github.com/OpenStreetMapSC/MergeAddressesAndBuildings . All usable tags in the source data have been mapped to OSM attributes. Data consisting of new and edited has been prepared for a JOSM upload. For an example of the complete data, see https://greenvilleopenmap.info/GreenvilleData/MergedOSMData.osm . Note that this is before validation - there will be some overlapping buildings and duplicate address nodes.

A preliminary conflation with existing data has been performed by the MergeAddressesAndBuildings program cited above. There are remaining edge cases that must be corrected before upload and will be detected with the JOSM validator and upload review procedure below.

Approach

The dedicated accounts to be used for the import are named GreenvilleSCCityImport1 and GreenvilleSCCityImport2, and GreenvilleSCCityImport3. Three local mappers have expressed an interest in helping with the import.

The project will be coordinated via the OSM US Tasking manager using the project https://tasks.openstreetmap.us/projects/232 , which contains instructions. For each square, perform the following -

  • JOSM only
  • Click the link in the "This task involves loading extra data" message to download data for the square.
  • Merge new layer with newly downloaded OSM layer by selecting both, right click and choose "Merge".
  • Use the JOSM "ToDo plugin" to review proposed list of building changes - search for the string "building modified OR new" , then press "Add" on the ToDo plugin to create a list of new and modified buildings to review.
    • Some existing buildings will not be automatically edited if:
      • last edit was newer than a certain date assuming that recent high quality imagery results in better building outlines.
      • the existing building is replaced by a much larger or smaller building.
      • either old or new buildings share nodes with a neighbor building
      • either the old or new building is a multipolygon
    • A building with poor geometric quality can be either manually edited or copied from the raw GIS file at https://greenvilleopenmap.info/GreenvilleData/GreenvilleCityBuildings.osm and fixed using the "Replace Geometry" function.
  • For multi-family buildings, rearrange address nodes as necessary to fit within building outline.
  • Remove buildings which have been torn down.
  • Press upload and review JOSM validation warnings:
    • For duplicate addresses, choose the "main" building and remove the address from any outbuildings.
    • Fix crossing buildings and waterways, fix crossing buildings and highways, correct other warnings about buildings.
    • Possible version conflict; a building edited since the import project was created will create a version conflict. Generally, use 'their' version and check the building and address to be sure the final result is correct.
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