FOSS4GNL 2026: Back in Groningen, Back with the Community

Nine years ago, we held the very first FOSS4GNL in Groningen. This year, we returned, and it felt like coming home. Thanks to the generous support of the Jantina Tammes School of Digital Society, Technology and AI at the University of Groningen, we enjoyed two inspiring days in their beautiful venues.

The organisation team, Gert‑Jan van der Weijden (OSGeoNL), Lars van Tol (OSGeoNL), Raymond Nijssen (QGIS Gebruikersgroep Nederland), and Leon van der Meulen (Geodienst University of Groningen), did an outstanding job. I was part of the Programme Committee, together with Ronnie Lassche (Merkator) and Derek van Bochove (Geon), and with this great team we created a programme that truly showcased the strength of the Dutch open‑source geo community: 12 workshops and 41 talks.

The workshop day welcomed 50 participants, and the conference day was completely sold out with 170 participants.

8 July: Workshop Day at Het Groot Handelshuis

I started the workshop day with my session on the new GDAL Command Line Interface. After a short introduction, participants worked through the tutorial, which is still freely available on GIS OpenCourseWare (English/Dutch).

After lunch, I gave my workshop on Point Clouds in QGIS, where participants explored 3D visualisation and analysis. It was great to see how much they learned from each other. This workshop is also available on GIS OpenCourseWare (English/Dutch).

Later in the afternoon, Peter Schols delivered the workshop GeoAI in Action, which we prepared together as part of the collaboration between Geo‑ICT Training Center and QWAST. This workshop is also available at GIS OpenCourseWare (in Dutch).

I also joined the fascinating workshop on OpenRiverCam by Hessel Winsemius (Rainbow Sensing). Using video as a sensor to monitor water levels, velocities, and discharge is incredibly powerful. With his Python package PyORC, I could easily calculate river velocity in a Jupyter Notebook and visualise the mesh in QGIS.

All these workshops are part of broader courses that can be delivered in various formats (online, blended, individual, or in‑house). Feel free to contact me if you're interested.

We ended the day with drinks, followed by a lively Ice‑Breaker Party at The Dog's Bollocks.

9 July: Conference Day at the Rölinggebouw

The second day began with a welcome from the OSGeoNL board, followed by Nolda Tipping‑Griffioen, CIO of the University of Groningen. She presented the university's ambitions around open source and digital sovereignty, a theme that continued in the keynote by Prof. Dr. Ronald Stolk, who highlighted both the challenges and the impressive initiatives Dutch universities and SURF are working on.

After the coffee break, I presented on making cities more liveable with FOSS, focusing on the 3+30+300 rule. The audience responded enthusiastically, especially to the open datasets produced by the Friedenau Society that can be freely downloaded from KlimaatEffectAtlas. Source code is avaible at the Codeberg repository. In the same session, Marij Dekker (Geolanda) gave a great talk on NDFF nature data and how to visualise it in QGIS.

Before lunch, we gathered on the stairs of the Academy Building for the traditional group photo. 

After a nice lunch, I attended Raymond Nijssen's (Terglobo) presentation on Windmill Biotopes, a very Dutch case study on ensuring windmills remain functional and visible as cities grow. His tools, built with QGIS, Python, Blender, and Cesium, looked impressive. This was developed for Provincie Zeeland.

Next was a presentation on the LEIA open‑source digital twin platform, developed by Provincie Zeeland and Sogelink, followed by Erik Meerburg (VNG) on Open 3D governance at municipalities. Gerlof de Haan and Derek van Bochove contributed to the presentation that provided insights from research by GIMA students.

After the tea break, I presented on using Mergin Maps to improve canvassing during elections, sharing results from a pilot for GroenLinks‑PvdA (now PRO) during the March 2026 municipal elections. 

Meanwhile, Laura Alejandra Agudelo (IHE Delft) presented on FAO WaPOR open data and open‑source tools supporting Colombia's National Water Study. Her attendace was funded by the QGISHydro Book Fund.

I also attended a talk on RUG Maps for indoor navigation by Tom Verhage and Auke Molendijk, which offered valuable insights into user experience. The final presentation I attended was by Niels Wouda, who introduced PyVRP for solving vehicle routing problems with interesting examples such as optimising garbage collection in municipalities.

We closed the day with drinks in the garden of the beautiful Academy Building. A wonderful ending to an inspiring event.

Looking Back

FOSS4GNL 2026 was a fantastic opportunity to reconnect with familiar faces and meet many new open‑source geo enthusiasts. Having FOSS4G Europe and FOSS4GNL back‑to‑back was a bit tiring, but I enjoyed every moment!