Import/Loudoun County, Virginia Buildings

This is a plan for the addition of building footprint data for Loudoun County, Virginia. This effort builds on imports that were completed earlier this year for the City of Redlands, California and City of Flagstaff, Arizona using data preparation procedures developed for those efforts and refined based on OSM community feedback, with a different process for mappers to add the features to OSM (see Data Updates section below). For a list of other Esri-curated datasets that are available for mapping, please see Esri ArcGIS Datasets.

Goals

The goal of this effort is to add the Loudoun County buildings data to effectively complete the coverage of building footprints for the County, using authoritative data from the County. This effort would greatly enhance the coverage of buildings for the County, while retaining the many buildings already added to OSM. The County buildings data includes a few fields that can be added as tags.

Schedule

Data preparation was performed in November 2020. The edits to OSM would be performed incrementally by OSM mappers over 2021, starting after data is reviewed by the OSM community.

Source

The source building footprints were assembled in September 2020 as part of Esri Community Maps Data (v1.0), made available by the County through Community Maps Data Sharing.

The processed building footprints that could be added to OSM are available to access on ArcGIS Online (see Loudoun County, VA Buildings). You can Open in Map Viewer to preview (click features to view tags) or sign in to export data for offline use.

OSM ODbL Compliance: Yes, the data is provided under a CC-BY 4.0 license, with explicit waiver for use in OpenStreetMap as defined by LWG.

Data Preparation

The processed building footprints referenced above were created using these Esri Data Processing Steps for Buildings and Addresses, developed and refined while doing data prep for several city and county communities in the United States. Below are a couple notes specific to the Loudoun County buildings data data.

• The processed building footprints data contains 120,013 buildings, many of which do not already existing as building features in OSM.
• The data includes a couple fields (building, addr:state) that have been prepared to be added as tags in OSM.

Data Conflation

Existing building features in OSM will not be replaced. The plan is to perform the updates in phases. In the first phase, only new buildings that do not intersect existing buildings will be added. In future phases, existing OSM buildings may be updated to include additional tags.

Data Updates

The plan is to perform the initial phase of updates using an updated version of RapiD and an updated Map with AI plugin for JOSM (see Esri blog post on new tools in OSM editors for more detail). The new tools enable OSM mappers to access ArcGIS Datasets hosted in ArcGIS Online and select individual features to use while editing OSM. The mapper is able to select a feature, review and edit the feature geometry and available fields, and then save their edits.

The mapper has the benefit of using existing features that have been created by the data provider, along with their available field values that have been pre-processed by Esri, while also being able to compare that feature with existing OSM data (e.g. street names) and imagery to ensure it is accurate and consistent. The data source used for the edit will be added as a tag to each feature that is saved as part of a changeset (unless deleted by the mapper).

Accounts

The plan is for most OSM mappers to use their standard OSM accounts if they are editing with RapiD and JOSM editors for OSM and editing individual features. However, if Esri staff were to do any 'bulk' edits where we do not examine individual features, then we will create and use new dedicated import accounts (e.g. <username>_loudoun_import) for those changesets. We encourage other OSM mappers to do the same.