In this paper, we propose an OBDA approach for accessing geospatial data stored in relational databases using the R2RML mappings and OGC standard GeoSPARQL. On the theoretical side, we provide a formalization of GeoSPARQL in terms of SPARQL entailment regime. For a practical query answering algorithm, we introduce an extension to the existing SPARQL-to-SQL translation method to support GeoSPARQL features. Our approach has been implemented in the system Ontop-spatial, an extension of the OBDA system Ontop for creating virtual geospatial RDF graphs on top of geospatial relational databases. We present an experimental evaluation of our system using and extending a state-of-the-art benchmark. To measure the performance of our system, we compare it to two state-of-the-art geospatial RDF stores –a free and open-source one, and a commercial one– and confirm its efficiency.

在本文中，我们提出了一种OBDA方法，用于使用R2RML映射和OGC标准GeoSPARQL访问关系数据库中存储的地理空间数据。从理论上讲，我们根据SPARQL包含机制提供了GeoSPARQL的形式化。对于实用的查询回答算法，我们引入了对现有SPARQL到SQL转换方法的扩展，以支持GeoSPARQL功能。我们的方法已在系统Ontop-spatial中实现，该系统是OBDA系统Ontop的扩展，用于在地理空间关系数据库之上创建虚拟地理空间RDF图。我们使用并扩展了最新的基准，对系统进行了实验评估。为了衡量我们系统的性能，我们将其与两个最先进的地理空间RDF商店进行了比较-一个免费和开源的商店，