A great team effort to map missing residential buildings in Germany was recently concluded. Many motivated mappers worked together to add 360,000 buildings all over Germany.

If you’d like to take part in the next round, come join the party at

➡️ MapRoulette: Add buildings in Germany!

Background

This mapping effort began when populated areas in Germany were identified that had neither buildings nor residential land use mapped. A MapRoulette challenge was set up and 14,330 new land use areas and 17,440 buildings were mapped in only 43 days. You can read about the details in my previous blog post MapRoulette: Unmapped residential areas in Germany.

This blog post is about the second round that started afterwards in January 2021.

Procedure

The idea was to find residential or farm yard areas without any buildings. These should contain buildings for sure, or the land use information should be corrected. (Later it turned out that farmyards without fixed buildings are legitimate.)

To this end I imported the Germany dump of OSM into a PostGIS database while already filtering for the desired land use and building types. In PostGIS I spatially intersected the buildings with the land use polygons and removed all land use areas which touched any building.

… See full entry

While working with the high-resolution data of the German census 2011, I noticed that there are still surprisingly many residential areas that are neither recorded as landuse=residential nor as building=*. This concerns mainly linear settlements or farms in the northwest of Germany.

There is now a MapRoulette-Challenge to map at least the landuse for these areas:

Unmapped residential areas in Germany

Please jump in and help if you are interested!

As a source for the challenge I compare the 100m×100m grid cells with the landuse and building polygons, which indicate residential areas: landuse=residential, but also landuse=farmyard, landuse=allotments and some more. For the buildings the residential types building=detached, building=house, etc. are used, but also building=yes.

In the process all census raster cells are deleted, which are at least touched or covered by these polygons. Then all clusters of connected grid cells are combined into one polygon. Of these, again only those are used, in which there are at least 12 persons living according to the census and which contain at least 2 raster cells. The priority of the tasks is set according to the number of inhabitants, so that “worse” cases are presented first in MapRoulette.

With this rigorous filtering I hope that really only the legitimate cases will be left. After all, there are still 2760 cases, so enough to do. The 2011 census is already quite old. Where several people lived 10 years ago, hopefully some of them will still live today.

A map of the mainly affected areas in northwest Germany:

… See full entry

Der Tagesspiegel bringt legt seinen Zeitungen alle Jahre wieder die „Radpartie“ bei. Das sind wöchentliche Serien mit jeweils einem Radtouren-Vorschlag mit Karte und Beschreibungstexten als kleines Faltbooklet zum Mitnehmen.

Neu ist dieses Jahr, dass Openstreetmap-Daten als Grundlage für die Karten dienen. Sie haben zwar Ihren eigenen Kartenstil, aber an manchen Details, wie z.B. dem ultragenau erfassten Golfplatz im Bild unten, kann man es dann doch erkennen.

Neu ist außerdem die Kooperation mit komoot, einer Wander-/Rad-Navi-Software für’s Smartphone, die ebenfalls auf OSM-Daten basiert. Man tippt einen Gutscheincode in die App ein und bekommt die vorgeschlagene Route gleich in der App angezeigt.

Hier ein Kartenausschnitt: