Import/New Zealand Buildings
This is an overview of the addition of building outline data for New Zealand. The data has been provided courtesy of Land Information New Zealand (LINZ) for use in OSM. 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 allow contributors to use New Zealand Buildings Outline data to continue to expand to the coverage of buildings across the country, using this data from LINZ which has near-total coverage of the country. This effort would facilitate the task of increasing coverage, while retaining the many buildings already represented in OSM.
Schedule
Data preparation was performed in April 2021. This OSM-ready data was reviewed by the NZ OSM community for its suitability to be imported through editor tools such as RapiD.
The data was updated using the data from LINZ dated 30 March 2020, and released onto the RapiD platform in April 2021. The edits to OSM are to be performed incrementally by OSM contributors, performing manual imports of the data in RapiD or JOSM.
Progress
This OSMCha filter can be used to track the addition of the LINZ building dataset. The filter displays changesets in New Zealand which have mapwithai as a source. This source value is added when using the RapiD editor. At time of writing, these changesets entirely consist of users adding the LINZ building datasets.
An update on the import was provided as a lightning talk at the 2023 FOSS4GSotM Oceania conference. Video recording available on Youtube
Source
The source building outlines are downloaded from ArcGIS Online (first release from data dating from 30 March 2021, with a refresh in September 2023) at the suggestion of the OSM NZ contributors and LINZ, for the purpose of preparing for adding to OSM via editor tools such as RapiD. The LINZ Data Dictionary describes the original dataset in detail.
The processed building outlines that could be added to OSM are available to access on ArcGIS Online (see New Zealand 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. File:LINZ_OSM-CC-4.0_waiver.pdf
Data Preparation
The processed building outlines were created using these Esri Data Processing Steps for Buildings and Addresses.
The data has initially been prepared for community review with two tags on each feature: building=yes ref:linz:building_id={building_id}. A source=esri/LINZ_NZ_Buildings tag would also be added at the time of editing. More fields are available in the original dataset, and can be considered for inclusion as tags:
| Original Field (LINZ) | Example | key in imported OSM feature | Note |
|---|---|---|---|
| building_id | 3926418 | ref:linz:building_id | Following same schema used with other LINZ imported features |
| use | Unknown | - | This tag is populated for a small amount of supermarket buildings. This could have been represented by including the tagshop=supermarketon these features. As this would be a minority case, not included for data simplicity and consistency.
|
| name | - | As above, name only contains a value for some supermarkets. | |
| suburb_locality | Grafton | - | Not included, as address details are separately imported and represented as address points. These can be merged onto buildings by contributors. |
| town_city | Auckland | - | |
| territorial_authority | Auckland | - | |
| capture_method | Feature Extraction | - | |
| capture_source_group | NZ Aerial Imagery | - | |
| capture_source_id | 1014 | - | |
| capture_source_name | Auckland 0.075m Urban Aerial Photos (2017) | - | Was considered for source tag on the feature, not included. |
| capture_source_from | 2017-03-15 | - | Not included |
| capture_source_to | 2017-05-06 | - | |
| last_modified | 2019-03-28 | - |
Data Conflation
The processed building outlines data contains 3,258,578 buildings, most of which do not already existing as building features in OSM.
Existing building features in OSM will not be replaced, because RapiD will only suggest the addition of buildings where there is no overlap with an existing building feature. OSM New Zealand contributors will be able to use tools such as RapiD to add new buildings using the processed buildings from LINZ and to make adjustments to the building geometry and attributes based on local knowledge and the most current imagery. This process has a high degree of human oversight. This should improve detection of cases where a feature may be a false-positive, for example if it the building been demolished since the source imagery date, or if it was not a building to begin with (caravans, containers)
Data Updates
The plan is to perform the updates using a 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.
Discussion
The proposal to add LINZ building outlines to the Esri-curated datasets is being discussed on the Talk-nz OSM mailing list: https://lists.openstreetmap.org/pipermail/talk-nz/2021/000239.html