3CIM

3D city models is an area with a high rate of development.

In early days, they were solely used for visualization and functioning as a backdrop for city planning proposals but now there is a demand for the models to form a basis for the digital twins of cities.

Digital twins are required not only for visualization but also for analyses and simulations of various scenarios and as such, they have the potential to significantly improve municipal processes in order to meet societal challenges such as climate change and security.To meet those demands, the 3D city model needs to be object based and semantic - the objects need to be sorted into classes and have relevant attributes.

Moreover, it should be possible to access other data connected to the objects from the 3D city model.

During the years 2020 through 2022, the 3CIM project (run by the city planning administrations of Gothenburg, Malmö and Stockholm along with Lund university) has worked on producing an information model for precisely that sort of 3D city model.

The workflow was iterative and a large part consisted of creating test data and evaluating the information model with different use cases. The information model is based on open standards and can be technically implemented using open source products.

Results have recently been published on the Smart Built Environment website (https://www.smartbuilt.se/projekt/informationsinfrastruktur/3cim/) and there has been great interest from other municipalities and national authorities.In this project we want to continue building on the results of 3CIM in three parts: 1) implementing 3CIM by fully structuring our data according to the information model and use it in municipal processes of the built environment, 2) further investigation of some aspects identified by 3CIM, and 3) establishing a long-term stabile management of the information model, responsible for further development and for support to other municipalities wanting to implement the 3CIM model.Working with 3CIM, we have seen great interest from other municipalities expressing the need for standardizing 3D city models. 3CIM results are openly available and can be implemented in other municipalities.

However, we think that a supporting organisation that municipalities can turn to can greatly facilitate implementing the model.

Developing the technical implementation in the database management system 3DCityDB (open source), an aspect that this project wants to delve deeper into, will make it easier for everyone to create their 3D city model using 3CIM structure.

The full-scale implementation of the information model in Gothenburg, Malmö and Stockholm enables us to identify possible problems at an early stage and solutions can be made useful for all municipalities following.