Due to rapid developments in innovation and digitization, several Dutch cities are taking their first steps into the world of 3D. The Municipality of Groningen is one of the municipalities leading the way in this. After a symbolic key handover of the digital city, the municipality now has a fully-fledged 3D Digital Twin.
^ Picture: municipality of Groningen – Henk Tammens
Virtual Groningen
The construction of a full-fledged 3D Digital Twin begins with laying down a vision. In collaboration with various stakeholders, the Geo & Data department drafted the document "virtual Groningen."
The vision document aligns with the municipal vision of which the Environment Act, the use of open data and the insightfulness of the subsurface and environment are important pillars.
The Municipality of Groningen faces an increasingly complex task when it comes to the layout and management of the spatial area. Construction projects are becoming more complicated and both the surface and subsurface are becoming increasingly crowded. One of the carters, Andries Nolles Technical Specialist 3D GEO & Data is very proud of the realization of the 3D Digital Twin:
"The 3D Digital Twin ensures that spatial projects can be carried out faster, cheaper and more transparent. Use of the 3D Digital Twin significantly reduces the risk of failure costs and helps with imaging."
The 3D Digital Twin is being used for a number of major spatial themes, including energy transition, sustainability and climate adaptation, traffic and transport, and living and working, among others.
Andries continues: "A 3D Digital Twin makes use of uniform, accurate and reliable data, which reduces the chance of error-prone conversions. The data is collected once and can be used endlessly for various analyses such as heat stress and flooding. This saves process costs."
"The consortium proceeded like a smooth train"
Consortium
For the realization of the Digital Twin, Future Insight, Plot 10 and Avineon joined together in a consortium and worked together to create the full-fledged 3D Digital Twin.
Construction 3D Digital Twin
The two-year process, to arrive at a 3D Digital Twin, was divided into 3 different phases; the city center, the surrounding neighborhoods and finally the suburbs.
The Municipality of Groningen made high demands on the accuracy of the Digital Twin. To meet these requirements, Kavel 10 realized an 80/80% overlap for the city center and an 80/60% overlap for the other neighborhoods. In addition, a ground sample distance (GSD) of 2.5 centimeters for the center and 5 centimeters for the remaining neighborhoods was used. Finally, LiDAR, nadir and oblique images were acquired in 1 flight.
Based on the detailed data from Lot 10, data modeling partner Avineon created the CityGML models of buildings, bridges and boundary walls with varying levels of detail. For the city center, LOD 2.3 was the requirement and for the other neighborhoods it was built with LOD 2.0. In doing so, Avineon modeled underpasses (OCS) and roof terraces (OFS) for all neighborhoods. In the city center, bridges were additionally modeled. To increase the level of realism, the Digital Twin was fully textured.
The large amount of data available, makes it necessary to make choices in using the right data. Future Insight, from its role as process supervisor, advised in the use of the data standards, the required quality and the processing of the supplied data in the 3D City database. From this database, which is based on CityGML, the data is accessed and displayed in a viewer: the Virtual City Map. Future Insight has also provided various training courses on the use of the Virtual City Map and the 3D Digital Twin in general.
"Mirella Hilgenkamp, Director of Project Management at Future Insight is very enthusiastic about the process, "The consortium proceeded like a smooth little train. Within our consortium we created a collaboration that was based on trust and a clear common goal. This enabled us to continually make the right choices and move quickly. And equally important: this made it a very fun and inspiring project to work on together!
