Montréal/Imports/Arbres publics

Montreal tree import is an import of the City of Montreal's Arbres publics sur le territoire de la Ville dataset.

Goals

The goal is to import nodes for the above feature in cases where they are missing in the existing OSM data for the territory of the City of Montreal. This amounts to 295 535 trees.

Import Data

Background

Data source sites: Arbres publics sur le territoire de la Ville
Data license: Licence d’utilisation des données ouvertes de la Ville de Montréal (note the section "Utilisation des données par OpenStreetMap").
Type of license: CC-BY-4.0.
Link to permission: Montréal/Imports/Ville de Montréal.
OSM attribution: Contributors (see "Montréal").
ODbL Compliance verified: yes.

Import Type

This is a one-time import that will be added to the OSM database via JOSM.

Plans for how this large dataset can be updated in the future are detailed below.

Data Preparation

Tagging Plans

The species field ("Essence_latin" in the source dataset) was not included as there are 752 unique variations. Some of these are in fact genus names and not species names. Moreover, a large proportion of these 752 unique values contain nonstandard species or genus names and/or presumably indicate a hybrid species.

The circumference tag in the source dataset ("DHP") was not included for two reasons: it is measured at 1.4 m above the ground (rather than 1.3 m for OSM) and, more importantly, many of the survey dates for this ever-changing measurement are many years out-of-date.

As a result, the only OSM-compatible information that can be imported is their location.

Changeset Tags

Key	Value
comment	Import of trees from the City of Montreal's dataset, with additional steps to avoid duplicating existing OSM data.
import	yes
source	Ville de Montréal
source:url	https://donnees.montreal.ca/dataset/arbres
source:date	2024
import:page	https://wiki.openstreetmap.org/wiki/Montréal/Imports/Arbres_publics
source:license	CC-BY-4.0

Data Transformation

1. Download the Inventaire arbres publics - Fichier consolidé csv file.
2. Open as a delimited file in QGIS. The fields "Coord_X" and "Coord_Y" are the X and Y fields respectively.
3. Freehand select the points within the territory of the City. Export this selection as a geojson in WGS 84. Do not export any of the fields.
4. Open the most recently created file in JOSM and tag as natural=tree.

Data Merge Workflow

Workflow

Conflation

1. In JOSM, download as a new layer "natural"="tree" using Overpass for the relevant extent (larger than the territory of the City).
2. In the conflation plugin, freeze the import data as the reference and the existing tree nodes as the subject. Use disambiguation, centroid < 7.0 m and do not replace geometry. Conflate.
3. Conflate those in the "Reference only" category (those not already present in OSM).

Changeset Size Policy

In JOSM, upload objects in chunks of size: 9980.

Revert Plans

If ever something goes wrong, the JOSM/Plugins/Reverter plugin will be used.

How to Update This Import in the Future

1. Open a more recent version of this same import dataset in JOSM. It can be replicated by following the four steps in the Data Transformation section. Select all nodes and freeze as the reference for conflation
2. Download "natural"="tree" as a new layer using Overpass for the relevant extent. Freeze this layer as the subject for conflation.
3. Run conflation. The conflation settings (such as the centroid distances) can be tweaked depending on if tree placement was refined in the future version of this dataset.
4. If a node is present only in the reference dataset, then we can assume that it is a newly-added tree and should thus be imported.
5. With the layer from step 2 (existing OSM trees) as the active layer, search for the following: User:Spearfish7424 AND "natural"="tree" and timestamp:2024-07-04. Make this the reference in the conflation plugin.
6. Make the layer from step 1 the subject of the conflation. Run conflation once more.
7. If a node is present only in the reference dataset, then we can assume that this tree has been removed as it is no longer present in the more recent version of the dataset it originated from. These trees can be deleted. Remember to preserve geometry if the node is part of a way or relation (delete only the natural=tree tag).

See also

A related post, about a more complex import from the same source, was sent to the community forum on 2024-01-29 and can be found here.