Category: OpenStreetMap

Public profiles on “How did you contribute to OSM?”

The web page How did you contribute to OpenStreetMap? (HDYC) provides individual detailed information about project members. Some time ago, the page has been revised, that member profiles can only be accessed, when users logged in with their OpenStreetMap (OSM) user account. This feature has been implemented, after a long and important discussion about “protecting user privacy in the OSM project”. The complete German discussion can be found here. However, I don’t want to continue the discussion here. I still support that any information, which are available about contributors, should not be hidden in project data dumps, APIs or on webpages. In my opinion, information such as contributor names or ids and modification timestamps are essential for doing quality analysis and assessments to protect the project against e.g. vandalism or unintended map edits.

Processing compressed OpenStreetMap Data with Java

This blog post contains a summary on how you can write your own Java classes to process OpenStreetMap (OSM) pbf files. PBF is a compression format, which is nowadays more or less the standard utilized for reading and writing OSM data quickly. In the OSM world, many tools and programs implemented this file format (you can find additional information here). However, I think the following samples for reading and writing such compressed OSM data can be very helpful. In particular, if someone has to create some sort of test data or has to read some specific mapped objects of interest for her/his own project. The well-known Java Osmosis tool (command line application for processing OSM data), provides several libraries that are the basis for this brief tutorial.

Step 1: Maven is the key – If your Java project is already managed by Maven, you can just add the following lines to your pom.xml. It downloads and adds the required jar-files that are needed to process compressed OSM data to your project.

Review requests of OpenStreetMap contributors
– How you can assist! –

The latest version of the OpenStreetMap editor iD has a new feature: “Allow user to request feedback when saving“. This idea has been mentioned in a diary post by Joost Schouppe about “Building local mapping communities” (at that time: “#pleasereview”) in 2016. The blog post also contains some other additional and good thoughts, definitely worth reading.

However, based on the newly implemented feature, any contributor can flag her/his changeset and ask for feedback. Now it’s your turn! How can you find and support those OSM’ers?

  • Step 1: Based on the “Find Suspicious OpenStreetMap Changesets” page you can search for flagged changesets, e.g. limited to your country only: Germany or UK.
  • Step 2: Leave a changeset comment where you e.g. welcome the contributor and (if necessary) give her/him some feedback about the map changes. You could also add some additional information, such as links to wiki pages of tags (map features), good mapping practices, the OSM forum, OSM help or mailing lists. Based on the changeset comment other contributors can see that the original contributor of this changeset already has been provided with some feedback.

Who is commenting?
An Overview about OSM Changeset Discussions

As mentioned in my previous blog post about detecting vandalism in OpenStreetMap (OSM) edits, it’s highly recommended that contributors use public changeset discussions when contacting other mappers regarding their edits. This feature was introduced at the end of 2014 and is used widely by contributors today. Each and every comment is listed publicly and every contributor can read the communication and, if necessary, add further comments or thoughts. In most cases where questions about a specific map edit come up, it is desirable that contributors take this route of communication instead of private messaging each other.

For my presentation at the German FOSSGIS & OpenStreetMap conference I created several statistics about the aforementioned changeset discussion feature. For this blog post I reran all analyses and created some new charts and statistics. Let’s start with the first image (above): It shows the number of commented or discussed changesets per month since its introduction. The peak in January, 2017 is based on a revert with several thousands of changesets.

Detecting vandalism in OpenStreetMap – A case study

This blog post is a summary of my talk at the FOSSGIS & OpenStreetMap conference 2017 (german slides). I guess some of the content might be feasible for a research article, however, here we go:

Vandalism is (still) an omnipresent issue for any kind of open data project. Over the past few years the OpenStreetMap (OSM) project data has been implemented in a number of applications. In my opinion, this is one of the most important reasons why we have to bring our quality assurance to the next level. Do we really have a vandalism issue after all? Yes, we do. But first we should take a closer look at the different vandalism types.

Reviewing OpenStreetMap contributions 1.0 – Managed by changeset comments and discussions?

The OSM project still records around 650 new contributors each day (out of almost 5,000 registered members per day). Some countries (such as Belgium or Spain) already provide platforms to coordinate the introduction to OSM for new mappers. Others use special scripts or intense manual work to send the newly registered contributors mails with useful information (Washington or The Netherland). However, oftentimes new contributors make, as expected, beginner-mistakes. Personally, I often detect unconnected ways, wrong tags or rare fictive data. Unfortunately, sometimes (new) members also delete, intentionally or unintentionally, existing map data.

At the end of 2014, many people were anticipating the newly introduced changeset discussions feature. A few months later, I developed a page that finds the latest discussions around the world or in your country. By now, many OSM members use changeset discussions for commenting or questioning map edits of other members.

main

A comparative study between different OpenStreetMap contributor groups – Outline 2016

Over the past few years I have written several blog posts about the (non-) activity of newly registered OpenStreetMap (OSM) members (2015, 2014, 2013). Similarly to the previous posts, the following image shows the gap between the number of registered and the number of active OSM members. Although the project still shows millions of new registrations, “only” several hundred thousand of these registrants actually edited at least one object. Simon showed similar results in his yearly changeset studies.

2016members

The following image shows, that the project still has some loyal contributors. More specifically, it shows the increase in monthly active members over the past few years and their consistent data contributions based on the first and latest changeset:

2016months

However, this time I would like to combine the current study with some additional research. I tried to identify three different OSM contributor groups, based on the hashtag in a contributor’s comment or the utilized editor, for the following analysis:

Unmapped Places of OpenStreetMap – 2016

Back in 2010 & 2011 I conducted several studies to detect underrepresented regions a.k.a. “unmapped” places in OpenStreetMap (OSM). More than five years later, some people asked if I could rerun the analysis. Based on the latest OSM planet dump file and Taginfo, almost 1 million places have been tagged as villages. Furthermore, around 59 million streets have a residential, unclassified or service highway value. My algorithm to find unmapped places, works as follows:

  1. Use every place node of the OSM dataset which has a village-tag (place=village).
  2. Search in a radius of ca. 700 m for a street with one of the following highway-values: residential, unclassified or service.
  3. If no street can be found, mark the place as “unmapped”!

My results for the entire OSM planet can be found under the following webpage.

unmapped

Verified OpenStreetMap contributor profiles?

The reputation of a contributor in OpenStreetMap (OSM) plays a significant role, especially when considering the quality assessment of the collected data. Sometimes it’s difficult to make a meaningful statement about a contributor by simply looking at the raw mapping work represented by the number of created objects or used tags. Therefore, it would be really helpful if we would have some additional information about the person who contributes to the project. For example: Does she/he help other contributors? Is her/his work somehow documented or based on one of the “discussed” proposals? Or does she/he work as a lone warrior in the OSM world?

In 2010 I created “How did you contribute to OpenStreetMap?” (HDYC) as a kind of fun side project. Nowadays many people use it to get some detailed information about OSM contributors. Some of you are probably familiar with the “verified” icon used on some celebrity Twitter accounts. I created a similar new feature for the aforementioned HDYC page. If you connect your related OSM accounts, your profile will be marked as “verified”.

Good #Hashtags in OpenStreetMap Changesets

#Hashtags are commonly used on Twitter to find content for a specific topic. Also in the OpenStreetMap (OSM) universe they are popular and utilized to mark changesets, which have been contributed during a special event, such as mapping parties or HOT tasks. However, in most cases, they are added in the changeset comment section. Back in November, 2015, several people discussed the pros and cons about (only) this approach. You can find a general overview of good changeset comments here. The aforementioned wiki page also shows why it is important to write a “concise and adequate“ description of the edit. Anyway, I also support the opinion that we should not generalize this statement and only add hashtags in our changeset comments. I prefer the different approach in which the contributor adds an extra changeset tag for the hashtag(s). For example, the widely used JOSM editor allows optional tags (as you can see here). On the other hand, the iD editor, which is used in many cases by new contributors, doesn’t offer this feature. However, I am sure that with some minor changes this could be fixed. A more or less complete set of recommended or mandatory changeset tags can be found here.