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The new OSM Inspector

28.10.2008 | Jochen Topf

Mapping the world is not quite as easy as it looks and we need tools to help us do it. We need editors to input and change the data, but we also need some ways of checking whether the data we enter is correct (and we have to figure out what “correct” is supposed to mean in the OpenStreetMap universe). Of course, we have several maps already that give us a view of the collected data. But that is not enough. The “normal” maps on can’t show us every aspect of the data. Specialist debugging maps like the maplint view and the coastline checker have been used for a long time and have proven to be useful. But they are limited by the technology they use (Maplint is based on XSLT and rather slow) or by their scope (Coastline checker does only coastlines).

We here at Geofabrik have thought about this for a long time and experimented with different approaches. Today we are launching a new tool, the “OSM Inspector”. It is, hopefully, the beginning of a series of more powerful debugging tools. The OSM Inspector is basically a specialized map viewer that shows you different views of OpenStreetMap data.

The OSM Inspector is a framework into which any number of debugging views can be plugged. We initially offer three such views:

  • The “Geometry View” shows basic geometry problems.
  • The “Water View” shows lakes, rivers, coastlines, and other features related to water, and highlights possible problems.
  • The “Addresses View” shows addresses with house numbers mapped according to the Karlsruhe Schema.

Each of these views comprises a multitude of different layers than can be individually switched on or off, and each can be used on large and small map scales alike.

Launch the Inspector and select the Geometry view, zoom in to the area you want to check. You’ll find geometry anomalies (like self-intersecting ways) highlighted. Click an object to select it, and with another button click you’re in your favourite editor (Potlatch or JOSM) to fix the problem right away… across the three tools we’re starting with, you can individually select from more than 30 different pre-computed vector layers to help you debug an area. Whether you just want to care for your specific area and fix everything that is funny there, or whether you feel responsible for the waterways of a whole country and want to zoom in to problem spots from a high-level view, the OSM Inspector is your tool for hunting down bugs and fixing them.

To try out the OSM Inspector, point your browser at – no registration or installation required. Currently we only have data for Europe but we hope to cover the planet eventually. Also, OSM Inspector currently requires Firefox but we’re working on IE/Safari compatibility.

An example showing the different address view features is here:

Or  have a look at the incredibly well-mapped Prague:

This is only a start, more views will follow depending on what is needed and how much time we have. Tell us what you like about the views and what you’d like to see improved. What other views do you want do see? We’d love to hear from you.