Analysis of Interaction and Co‐editing Patterns amongst OpenStreetMap Contributors

OpenStreetMap (OSM) is a very well known and popular Volunteered Geographic Information (VGI) project on the Internet. In January 2013 OSM gained its one millionth registered member. Several studies have shown that only a small percentage of these registered members carry out the large majority of the mapping and map editing work. In this article we discuss results from a social‐network based analysis of seven major cities in OSM in an effort to understand if there is quantitative evidence of interaction and collaboration between OSM members in these areas. Are OSM contributors working on their own to build OSM databases in these cities or is there evidence of collaboration between OSM contributors? We find that in many cases high frequent contributors (“senior mappers”) perform very large amounts of mapping work on their own but do interact (edit/update) contributions from lower frequency contributors.     

Planar and non-planar topologically consistent vector map simplification

This article contains a mathematical analysis of strategies for determining topological consistency of vector map simplifications. Such techniques exploit assumptions that can be made regarding the similarity of corresponding objects in successive simplifications. We propose that all topological relationships may be classified as planar or non-planar. A formal analysis of techniques for determining topological consistency of a simplification in terms of such relationships is presented. For each technique we analyse any corresponding constraints that are imposed. This provides a unified understanding of the benefits and limitations of individual techniques and the relationships that exist between techniques. Subsequently, a new strategy for determining the topological consistency of a simplification is proposed. This technique integrates the benefits all methods studied to provide a solution which is subject to less constraints. The effectiveness of this approach is demonstrated through fusion with an existing simplification technique resulting in simplifications that have equal topology and similar shaped features to the original map.     

The Annotation Process in OpenStreetMap

In this article we describe the analysis of 25,000 objects from the OpenStreetMap (OSM) databases of Ireland, United Kingdom, Germany, and Austria. The objects are selected as exhibiting the characteristics of “heavily edited” objects. We consider “heavily edited” objects as having 15 or more versions over the object's lifetime. Our results indicate that there are some serious issues arising from the way contributors tag or annotate objects in OSM. Values assigned to the “name” and “highway” attributes are often subject to frequent and unexpected change. However, this “tag flip‐flopping” is not found to be strongly correlated with increasing numbers of contributors. We also show problems with usage of the OSM ontology/controlled vocabularly. The majority of errors occurring were caused by contributors choosing values from the ontology “by hand” and spelling these values incorrectly. These issues could have a potentially detrimental effect on the quality of OSM data while at the same time damaging the perception of OSM in the GIS community. The current state of tagging and annotation in OSM is not perfect. We feel that the problems identified are a combination of the flexibility of the tagging process in OSM and the lack of a strict mechanism for checking adherence to the OSM ontology for specific core attributes. More studies related to comparing the names of features in OSM to recognized ground‐truth datasets are required.