In the 3CIM project, the City Planning Administrations in Stockholm, Gothenburg and Malmö, together with Lund university, have created an information model to form the basis of a digital twin of a city. The purpose of having this as a mutual venture was, apart from sharing competense and resources, also to ensure a result that is more easily applicable for other municipalities in Sweden. The project has been conducted within the Information Infrastructure area of Smart Built Environment.
The final report is in Swedish. You can read the full report, and articles (in English) etc, on the Swedish project page.
The project started with an inventory of the requirements of a digital twin of a city to identify which data sets are important. These sets were grouped into themes, which have then been modeled. Test data have been created and verifications of the information model have been performed using test cases of flooding analysis, noise analysis and visualization. The verifications, as well as dialogue with the reference group of the project, have given insights and conclusions that have resulted in adjustments of the information model. Test data have then beed updated accordingly and the verifications run again. This iterative workflow has resulted in the, for the project final, information model 3CIMver1.0.
The information model is in accordance with the international open standard of CityGML2.0 and is designed as an Application Domain Extension, ADE. It consists of physical features of the urban space in a number of themes such as transport, building and bridge. For many use cases, a large amount of information connected to each object is required. However, it is hard to have an information model covering ”everything” without making it ungainly and difficult to implement. As a response to that, 3CIM has aimed at a relatively thin central information model, containing only information of the kind of object, its spatial coverage (in 3D) and visual attributes, such as surface material. In addition there is an abundance of information about objects in various operating systems and registers, within the municipality as well as at other actors. The 3CIM information model therefore utilizes connection to these other data sources in order to enable retrieving the information required for different uses without reduntantly storing the information and risking it to diverge from its original source.
A signifikant part of the project has been to produce test data for the practical verifications of the information model. Test data has beed created in one area each per city using existing basic geodata and to some extent new data collection. These data sets are made openly available as a part of the projects results.
FME scripts have been created for technical implementation of the information model and these are also made available. The scripts handle extending a 3DCityDB with the ADE of 3CIMver1.0 and import of 3CIM structured data in files to the database.
This final report can be read as three parts, with an introduction (chapters 1-3) describes background and purpose as well as the organization of the project. Relevant background information that have had an impact on the design choices of the project is accounted for. After that, the main part of the report follows which is focused on the results (chapters 4-7). The information model is described, with special attention to the design choices that have influenced the model, together with other information 8 3CIM sets that we have explored in the project but have opted against them being included in the final information model. A full despription of the information model can be found in appendix 2. Test data is described as well as the verifications of the information model that have been conducted using those test data. For visualization, a relatively detailed description of the processes involved is included. Having used av variety of visualization tools, we want to show the pros and cons we have encountered in order to, hopefully, provide relevant information for other municipalities that use one of several of these tools. Finally, there is a concluding and forward-oriented part (chapters 8-9), where conclusions and thoughts of further developments in the area are recorded.
The project concludes that there is a large benefit in a mutual data structure and that the 3CIM information model by and large has worked well for the use cases. However, there is great potential for further work in developing the model and spreading the results. Some aspects also require further investigation, for example how land cover and land use can be represented and how best to handle terrain models in relation to modeled objects.
ID: U8-2020-10
Call: Utlysning 8
Project manager: Maria Uggla, Stockholms stad