1,721,080 research outputs found
Crowdsourcing landforms for open GIS enrichment
No full textOpen Source Geographical Information Systems, such as OpenStreetMap (OSM), offer a valuable alternative to proprietary solutions for the development of voluntary environment monitoring systems. However, the quantity and quality of information stored in such systems must be carefully evaluated and the contributions of volunteers must be boosted by means of effective engagement methods. This paper reports the results of the assessment of the quality and quantity of OpenStreetMap mountain information: different types of information and world regions have different gaps and improvement requirements. To address this issue, we propose a hybrid approach, in which an open Digital Elevation Model data set is processed with a heuristic algorithm to find candidate mountain information and uncertainty in the automatically extracted candidates is reduced by means of voluntary expert crowdsourcing. The improvement of landform information (not only about mountains, but also about orography and hydrography in general) can support the development of environment monitoring applications
Leveraging label-independent features for classification in sparsely labeled networks: An empirical study
No full textAbstract. We address the problem of within-network classification in sparsely labeled networks. Recent work has demonstrated success with statistical relational learning (SRL) and semi-supervised learning (SSL) on such problems. However, both approaches rely on the availability of labeled nodes to infer the values of missing labels. When few labels are available, the performance of these approaches can degrade. In addition, many such approaches are sensitive to the specific set of nodes labeled. So, although average performance may be acceptable, the performance on a specific task may not. We explore a complimentary approach to within-network classification, based on the use of label-independent (LI) features – i.e., features calculated without using the values of class labels. While previous work has made some use of LI features, the effects of these features on classification performance have not been extensively studied. Here, we present an empirical study in order to better understand these effects. Through experiments on several real-world data sets, we show that the use of LI features produces classifiers that are less sensitive to specific label assignments and can lead to performance improvements of over 40 % for both SRL- and SSL-based classifiers. We also examine the relative utility of individual LI features; and show that, in many cases, it is a combination of a few diverse network-based structural characteristics that is most informative
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