~ Sampo-UI Meets Ontop: Publishing Relational Digital Humanities Data - Semantics 2026

The SEMANTiCS conference took place in Ghent from 15 to 17 September 2026. Our contribution was a collaboration between GhentCDH and the Semantic Computing Research Group at Aalto University on publishing humanities data with Sampo-UI and Ontop.

Sampo-UI Meets Ontop: Publishing Relational Digital Humanities Data on the Semantic Web, Joren Six¹, Jahid Chetti¹, Annastiina Ahola², Frederic Lamsens¹, Heikki Rantala², Eero Hyvönen²
¹ Ghent University, Ghent Centre for Digital Humanities (GhentCDH)
² Aalto University, Department of Computer Science, Semantic Computing Research Group (SeCo)

At GhentCDH, we often publish research datasets in the digital humanities. Several projects need similar search filters, map visualizations and data exports. Sampo-UI makes it possible to reuse these components when the data is available as Linked Data. In collaboration with the original Sampo-UI team, we worked on modernizing the framework. Our first contribution separates the shared core from project-specific configuration, making updates and reuse more manageable. The second uses Ontop to expose existing relational databases through a SPARQL endpoint. This lets us use Sampo-UI while keeping the database infrastructure and tooling we already have. Having one fewer database system to maintain is welcome.

Abstract: The Sampo model and its Sampo-UI framework have become an established approach for publishing Cultural Heritage and Digital Humanities data on the Semantic Web. Sampo-UI enables exploration of data originating from SPARQL endpoints through faceted search across multiple views with seamlessly integrated visualization and data analytic tools. Here, we present two contributions to the Sampo-UI ecosystem: (i) a separation of Sampo-UI core from application-specific configuration; decoupling core and application simplifies updates and facilitates reuse of efforts, and (ii) the use of Ontop — a virtual knowledge graph system — to expose relational databases through a SPARQL endpoint and Sampo-UI. The use of relational databases and reuse of tooling and expertise around relational databases lower the operational burden of publishing small-to-medium-sized datasets typical of digital humanities projects. These contributions originated outside the original Sampo-UI team but were developed in collaboration with it, and are being prepared for upstream integration. We illustrate the approach with two projects at Ghent University: one on Roman coin finds in Belgium (NuMAD) and one on historic Belgian company data (BelHisFirm). Both portals run the same Sampo-UI core with a different configuration, and operate on existing institutional relational database infrastructure without a dedicated graph database.

The demo below shows the NuMAD portal for exploring Roman coin finds in Belgium through the modernized Sampo-UI. Another demo presents historical records of Belgian companies through the BelHisFirm portal. Both portals run the same Sampo-UI core with different configurations, demonstrating the flexibility of the system.

Alongside the Sampo-UI Meets Ontop paper, a conference poster on Sampo-UI that I prepared is also available.

Video: NuMAD — exploring Roman coin finds in Belgium.

UGent, Code, Presentation, and GhentCDH