For the municipalities of Sweden: simpler, cheaper and smarter ways to develop the cities of the future. For VTI: more realistic driving simulators – and hence new, refined research. These are the long-term goals of the Visual Sweden City Platform project, for which VTI is a key partner.

The instruments are extremely expensive and located behind the vehicle, so before each job Thomas Lundberg has to start off by carefully reversing the new Mobile Research Platform – a road surface survey vehicle – out of the garage at VTI in Linköping. Then it takes up to fifteen minutes and a couple of tens of kilometres of driving before all the sensors are up and running and the operator sees a green light on the big screen in the cab.

Maybe you've seen the survey vehicle on its travels around the centres of Linköping and Norrköping recently? The vehicle has been used over a number of days to collect data that will be used to create digital twins as part of the Visual Sweden City Platform (VSCP) project, in which VTI is one of the collaborating organisations.

The vehicle has remained constantly in contact with satellites while performing the surveys, covering the city centres of Norrköping and Linköping, in order to determine the exact position of the vehicle.

"Surveys in urban environments are the hardest thing to do. The tall buildings mean that the satellites have to be more or less directly above the vehicle while you're driving," says Thomas Lundberg, the research engineer at VTI who drove the survey vehicle through the two cities.

The surveys use the vehicle's 360-degree camera and two LiDAR scanners to record the urban environments around the vehicle. The point clouds from the scanners, consisting of vast numbers of XYZ coordinates, create a digital description of reality in combination with the camera images. Each point in the image also has a unique, precise position.

The huge volume of image and point cloud data created from the surveys – VTI has delivered a total of 715 gigabytes – is then used to supplement other data already collected as part of the project. Data from satellites, aircraft, drones and bicycles, and even stationary scanners, has been used to create digital twins in the past.

"Supplementing this data is an important aim of our work, but the high precision and point density of our data makes it valuable for the VSCP project as well. Another goal is to make data available to other researchers. It hasn't been available before," says Thomas Lundberg.

The digital twins being created as part of the project will be used to develop the accessible and sustainable cities of the future. A 3D model makes it easy to test and try out various scenarios, simulations and changes to the urban environment. Compared to physical trials, and models, this makes a huge difference. According to the project website, the overall goal is nothing less than "to create the world's best, most advanced datasets for research and development in visualisation, image analysis and machine learning".

For VTI, there’s also a more immediate goal – to create more realistic simulator environments.

"Exactly how we’ll use the technology isn’t clear as yet. But our long-term goal is to make our simulators more realistic, and it's hard to come up with environments that are truly authentic. So in that case, it might be easier to use real-life surroundings in Norrköping and Linköping, for instance," says Mattias Hjort, research director and the man responsible for VTI's part of the project.

It's not possible to use a 3D visualisation directly in a driving simulator, but combining the models with logical descriptions of various objects and boundaries makes it possible to create an entire library of different simulator environments. These can then be used in future experiments that require a particularly high level of realism.

"Fictional environments work well in 95 per cent of our trials, and those don't have to be completely realistic. But then there are exceptions where we really need to represent a real road. In a best-case scenario, we'll be able to get better environments and it'll be faster, easier and cheaper to do so," says Mattias Hjorth.

Alongside this project, VTI has extensive experience of creating realistic simulator environments. This was done, for example, to review the driving experience in the Södra Länken tunnel in Stockholm when the tunnel was still at the planning stage. It's also been used to simulate heavy traffic on the narrow Töllsjövägen near Borås, where there have been numerous accidents.

Text: Mikael Sönne

Translation: CBG

Read more:

Visual Sweden City Platform (in Swedish) External link.

Mobile Research Platform, MRP External link.

LiU: "VTI is a key partner"

According to project manager Erik Telldén at Linköping University, VTI is a key partner in the Visual Sweden City Platform project: both a stakeholder with defined needs and an important enabler.

This combination of defined-needs stakeholder and enabler is precisely what makes the collaboration with VTI particularly interesting. On the one hand, VTI has unique driving simulators and a need to develop more realistic environments for these; while on the other, the road surface survey vehicle offers a unique opportunity to collect data and contribute to the project.

"VTI's data is by far the most detailed of all the sources we work with. Data was previously collected mainly from the air, by satellites or aircraft, but the survey vehicle gives us much more accurate data at ground level," says Erik Telldén, noting that LiU received a wealth of material to work with following the delivery from VTI.

There are several different technical solutions that can be used to convert raw data from scanners and images into 3D visualisations. Some rely on heavy data compression and relatively simple and crude descriptions of reality. These methods often suffice and may offer advantages in terms of lower costs and more established technology.

However, the project is currently focusing on exploring state-of-the-art technical methods. Such solutions provide incredibly realistic and detailed models in visual terms, but they also present major challenges when it comes to obtaining measurable information about the locations of different objects in the image. This is important, not least for VTI's driving simulators.

Besides Norrköping and Linköping, Malmö is also involved in the Visual Sweden City Platform project. Norrköping already has a digital twin of the entire municipality – which has been used to visualise the East Link project, among other things – which will be refined and developed. So far, Linköping is most interested in 3D models of Vallastaden and the campus area.

The project is being funded by Formas as part of the Smart Built Environment programme.