Chicago, Illinois/Buildings Import

This project to import Chicago buildings from a city-sourced GIS file is complete.

Goals

Import Chicago's excellent building footprints dataset to help Chicago mappers create a more effective map. Get highly accurate, city-wide address data.

Schedule

After an initial import of some buildings in May 2012, concern about license and lack of community discussion was raised by members of the Data Working Group so importing was paused. After Chicago re-released data under a more compatible license in February 2013, imports resumed. Ian led the import and plans to have it finished by the end of March 2013.

Import Data

Background

Data source site: https://github.com/Chicago/osd-building-footprints
Data license: https://raw.github.com/Chicago/osd-building-footprints/master/LICENSE.txt
Type of license (if applicable): MIT
ODbL Compliance verified: yes

OSM Data Files

Link to your source data files that you have prepared for the import - e.g. the .osm files you have derived from the data sources.

Import Type

Identify if this is a one-time or recurring import and whether you'll be doing it with automated scripts, etc.

Identify what method will be used for entering the imported data into the OSM database - e.g. API, JOSM, upload.py, etc.

Data Preparation

Tagging Plans

See the ogr2osm conversion script here: https://github.com/iandees/ogr2osm/blob/master/translations/chicago_buildings.py

Changeset Tags

I will set source=https://github.com/Chicago/osd-building-footprints on all changesets.

Data Transformation

1. Since the original data is distributed as GeoJSON, it needs to be converted to shapefile so I can chop it into manageable pieces.
2. Each "tile" of shapefile will be converted to OSM using ogr2osm and the translation I've written.
3. Each "tile" of OSM data will be manually merged with existing data (steps below).

Data Transformation Results

An example OSM file can be found here. Note that this is raw output from ogr2osm. Manual merging will take place in JOSM before uploading to OSM.

Data Merge Workflow

Team Approach

Ian will be converting and importing the OSM file tiles by hand, one by one.

Workflow

1. Fetch one tile of converted OSM data
2. Open it in JOSM
3. Download the corresponding area from the OSM servers as a new layer
4. Use manual inspection to look for features that overlap.
   • Toggle the OSM layer visibility to help spot overlaps.
   • Pay special attention to nodes that have building tags and existing schools (since they are frequently already mapped).
   • Make sure to delete buildings from the Chicago data when tags are copied from the import data to existing OSM data.
5. If changes were made to the data downloaded from OSM, upload those first in a separate changeset.
6. Upload the buildings into their own changeset.
7. Save the resulting OSM file to preserve the resulting OSM IDs.
8. Return to step 1.

Conflation

Since the OSM data is being hand-imported in manageable chunks, conflation with existing data will be handled manually in JOSM. I will prefer existing OSM data and tags over the imported data and will try to apply addressing tags from the Chicago data as correctly as possible.

QA

Add your QA plan here.