WikiProject Belgium/Road completion project

From OpenStreetMap Wiki
Jump to navigation Jump to search

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. If a project like [1] gains traction, that would help.

For a more general introduction, have a look at our project page

Our first dataset to use is Wegenregister, a Flemish public agency dataset containing all roads, paths and many driveways, derived from GRB, NGI and CRAB; both current and future that are known to the government. The geometric quality is excellent. Road attributes are not. The name is very reliable, though private roads that are tagged with a name do exist.

Processing code is at

Our first task is up. Check the Instructions page to get started!

Preparing & comparing data

Our approach

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. Built to be generic, it will be able to consume data from any road centerline source, such as from artificial vision or processed GPS data.

Comparison code lives here [2]. Current 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.

These roads are communicated to Maproulette, where they are turned into easy microtasks for mappers. The Maproulette process is essential, as it makes it easy to exclude false positives and wrong source data. Just offering maplayers would result in a wrong road being ignored until someone uncritically adds it to OSM.

In progress

  • rerun the analysis as much as needed, preferably up to minutely.
  • update the Maproulette Challenge accordingly
  • set up a system to extract Maproulette review data: to exclude them from re-runs and for secondary analysis, to communication to external datasource

In the future

  • find a methodology to also include road types that need local survey
  • tagging evaluation (name, road type)
  • reverse check: roads that are missing in official road data. This is especially useful for the open data source, but also leads to corrections in OSM.

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.

Related research

Subproject: ensuring all official named 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.

Alternative approaches


Using Postgis

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.

Offering services for OSM mappers

There is a first Maproulette task up!

  • Mapping layers. Available, but not communicated as they are prone to misuse.
  • Microtasking.

Maproulette still has some issues. Here are some how-to's:

This does NOT include comments, but those can be extracted by contacting the people behind Maproulette.

Using the API you should be able to download the current status and also upload new versions.

  • Fixed and false positives are still visible for all users. They can probably be removed and processed separately using the API.

This still needs resolving:

  • 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", except with Comments. The "Too hard" button is usually used to mark something as "unsolvable".