WikiProject Belgium/Road completion project
The Belgian community is building tools to make sure that any correction in the official open data road sets is made visible to the mapping community as quickly and as accurately as possible. As a first case, we would work with Wegenregister, from the Flemish government. But because it isn’t just Flanders that has released tools like this, we will try to build something that is easily scalable to any dataset of road centerlines worldwide.
For a better introduction, have a look at our project page
- Towards an Automated Comparison of OpenStreetMap with Authoritative Road Datasets, which also has a Github repository
Preparing & comparing data
Based on Mapbox QA tiles. First turn external data (Wegenregister in this case) into vector tiles. Ideally, this process can be plugged into a project like OSMlab's centerlines project.
Comparison code lives here  = Simple set-up: find roads that are probably geometrically missing in OSM.
In a later fase: generate errors by type, with different mapping solutions depending on the type
First focus roads that are both:
- "really missing in OSM"
- "named roads only", which are an easy category with very high quality. Already roughly 15-20.000 segments! This includes some paths, but in general "real" roads.
In the future:
- road types that need local survey
- tagging evaluation (name, road type)
- reversed check: roads that are missing in official road data
Subproject: ensuring all official roads are mapped at least once
A simplified approach: just check if all the official road names are on the OSM map at least somewhere. This detects both entirely missing roads and miss-spelled OSM roads.
1) Select all named roads by community in OSM Flanders
2) Select all named roads by community in Wegenregister Flanders
3) If a named road in Wegenregister is not available in OSM:
a) create a microtask for Maproulette fixing
b) create a dataset to feed a mapping layer
Note: sometimes, the name on the street sign might differ from the official road name. In gov logic, the official name is always correct. In OSM logic, the street sign is always correct. To allow for special cases like this, a tag indicating a different official name might be needed.
Cygnus, a tool developed by Telenav, allows for data conflation of external road datasets and OSM road data. Advantages: it allows for faster mapping, because the original geometry is copied. Disadvantage: it becomes a real import (hence procedures), people might be tempted to import as many roads as possible rather than checking case by case. Many of the differences will probably be complicated situations, making an automated approach rather difficult.
For OSM mappers
- Mapping layers. Similar to . Here as well, it might be useful to integrate with OSMlab centerlines somehow.
Maproulette looks promising, but some questions remain:
- extract geojson of tasks with their current status: http://maproulette.org/api/v2/challenge/[task number here]/tasks?limit=-1
- The task lists can be updated using an API call. E.g. you want to hide tasks that continuous geometrical checking notices are done. Looks like the only way is cloning, reloading data, and hiding the old version. Is this also the case when working with external data? If so, what happens to fixed tasks?
- Mark a task as "too hard" to group them for further analysis. However, not possible between "uh, I don't get it", and "needs a survey"
- Is it possible to lock someone within the task? In the test project, you tend to sometimes randomly arrive in a different task.
- are fixed and false positives removed from standard view (and is there a way to only see "advanced" tasks)?
- make it possible to leave notes to the manager: e.g. "yes, I fixed this, but something special is going on here"
- You can add a custom background map, which should be visible in the Maproulette interface.
- write proper instructions. Important to "also check with GRB", as this might still conflict with Wegenregister.
- add a Wegenregister background map to the task.
Sample task: http://maproulette.org/map/2467/ Sample dataset: https://www.dropbox.com/s/fhywx43437pwrvi/example.geojson?dl=0
Services for the data providers
- We will need a list of false positives to be able to remove these from further analysis. Otherwise, the same situation will be reviewed over and over again. If we make a difference between "just difference in drawing style" and "external data (Wegenregister) is wrong", then that same data is usable for external data managers to review their own dataset.
- Our mappers will focus on OSM quality first. But we could offer a package of services to local authorities to have an OSM-based validation of Wegenregister in their community. This would include training for civil servants, setting up specific tasks (Maproulette or Tasking manager) and helping out at a Mapathon where citizens are invited. This package should probably have a certain financial cost.