Governador Valadares/Projetos/Importações/Árvores e Postes
Governador Valadares Trees and Poles Import was an import of trees and poles datasets which are 2 files covering the city of Governador Valadares in Brazil, consisting of more than 46.000 trees and 20.000 poles. The import was successfully finished.
This project aims to import the trees and poles provided by the Governador Valadares city council, while manually conflating the existing trees/poles on OSM.
- October 2022: Preparation of the import proposal in the wiki and data testing and validation.
- November 2022: Disclosure in Community forum, talk-br list (both in Portuguese), discussion in the OSM Brazil Telegram group, and submission of the import proposal to the Imports List.
- November 2022: Annotation in the Import Catalog.
- November 2022: Import begin
- November 2022: Import end
Data source: Data was obtained by Addresses for All e-mails with the City of Governador Valadares, and then it was sent to us to be used on OSM.
Type of license: Public Domain, confirmed with municipality. The e-mails (link below) show explicitly that data can be used on OSM, since it is considered in Public Domain.
Link to permission: Explicit authorization.
OSM attribution: Prefeitura Municipal de Governador Valadares
The original files can be seen here.
OSM Data Files
The converted .osm files can be downloaded here.
This is a one-time import and JOSM will be used to review and upload the elements into OSM.
Data Reduction & Simplification
The data consists of two files that come as nodes, so there is no need for data reduction or simplification.
Since the original data has only the location of the trees and the poles, with no additional information, the following tags will be used, respectively:
- source = Prefeitura Municipal de Governador Valadares
- source:date = 2018
- comment = Importação semi-automática de árvores e postes de Governador Valadares
- website = https://wiki.openstreetmap.org/wiki/Governador_Valadares/Projetos/Importações/Árvores_e_Postes
The only transformation needed is to convert the tags to OSM tagging standard. That can be done by using QGIS or JOSM.
Data Merge Workflow
- Initially the data was evaluated regarding its quality. Based on visual analysis, it is of a high quality regarding completeness.
- Then, the data was checked regarding its positioning. Again, using aerial imagery, it is possible to see the good positioning of the nodes.
- Confirmed the quality of data, it must be conflated with existing data (see Conflation plan).
- After conflating all data, it must then be opened in JOSM.
- In JOSM, the data was validated. Lots of duplicates were found, and fixed with JOSM.
- Given the size of the file, JOSM will be done to upload the data. It automatically suggests to separate in batch of 1,000 elements to upload all trees and poles, so the OSM servers are not overloaded.
- If necessary, the changes will be undone using the JOSM/Plugins/Reverter plugin.
This is the strategy that will be done manually, to avoid conflicts with existing data:
- Initially a filtering must be made in Overpass Turbo, using this script, observing trees and poles that are already mapped in the OSM, and then remove those items from those provided by the Governador Valadares City Council.
- In principle, the trees and poles that are already mapped in the OSM must remain, as recommended. Eventually, if they are in significant disagreement, they can be complemented by those from the city council layer, maintaining the OSM data. The total replacement comes as a last case, to not lose the history of the previous node in the OSM.
It must be noted that only 2 trees were already mapped on OSM, and no pole. Therefore, all poles will be submitted without conflation and the 2 trees will be separated from the edited file, maintaining the ones from OSM.
After uploading to OSM, we can check some issues such as if a tree is exactly on top of a road. Given the high-quality accuracy (positioning), this data can be used to fix road and housing positioning, for example.
We would like to thank Prefeitura Municipal de Governador Valadares (Governador Valadares City Council), for allowing us to use their data. We would also like to express our gratitude to Mr. Thierry Jean, from Address for All, for sharing the data with us.