Abstract Aligning schemas and entities of community-created geographic data sources with ontologies and knowledge graphs is a promising research direction for making this data widely accessible and reusable for semantic applications. However, such alignment is challenging due to the substantial differences in entity representations and sparse interlinking across sources, as well as high heterogeneity of schema elements and sparse entity annotations in community-created geographic data. To address these challenges, we propose a novel cross-attention-based iterative alignment approach called IGEA in this paper. IGEA adopts cross-attention to align heterogeneous context representations across geographic data sources and knowledge graphs. Moreover, IGEA employs an iterative approach for schema and entity alignment to overcome annotation and interlinking sparsity. Experiments on real-world datasets from several countries demonstrate that our proposed approach increases entity alignment performance compared to baseline methods by up to 18% points in F1-score. IGEA increases the performance of the entity and tag-to-class alignment by 7 and 8% points in terms of F1-score, respectively, by employing the iterative method.

Abstract Semantic geospatial applications, such as geographic question answering, have benefited from knowledge graphs incorporating information regarding geographic entities and their relations. However, one of the most critical limitations of geographic knowledge graphs is the lack of semantic relations between geographic entities. The most extensive knowledge graphs specifically tailored to geographic entities are extracted from unstructured sources, with these graphs often relying on datatype properties to describe the entities, resulting in a flat representation that lacks entity relationships. Therefore, predicting links between geographic entities is essential for advancing semantic geospatial applications. Existing neural link prediction methods for knowledge graphs typically rely on pre-existing entity relations, making them unsuitable for scenarios where such information is absent. In this paper, we tackle the challenge of predicting spatial links in sparsely interlinked knowledge graphs by introducing two novel approaches: supervised spatial link prediction (SSLP) and unsupervised inductive spatial link prediction (USLP). These approaches leverage the wealth of literal values in geographic knowledge graphs through spatial and semantic embeddings. To assess the effectiveness of our proposed methods, we conduct evaluations on the WorldKG geographic knowledge graph, which incorporates geospatial data extracted from OpenStreetMap. Our results demonstrate that the SSLP and USLP approaches substantially outperform state-of-the-art link prediction methods.

OpenStreetMap is a rich source of openly available geographic information. However, the representation of geographic entities, e.g., buildings, mountains, and cities, within OpenStreetMap is highly heterogeneous, diverse, and incomplete. As a result, this rich data source is hardly usable for real-world applications. This paper presents WorldKG - a new geographic knowledge graph aiming to provide a comprehensive semantic representation of geographic entities in OpenStreetMap. We describe the WorldKG knowledge graph, including its ontology that builds the semantic dataset backbone, the extraction procedure of the ontology and geographic entities from OpenStreetMap, and the methods to enhance entity annotation. We perform statistical and qualitative dataset assessment, demonstrating the large scale and high precision of the semantic geographic information in WorldKG.