The new generation 3D city models, which the City of Helsinki has published as open data, provide application developers with countless opportunities for utilising city information. The semantic CityGML city information model contains information about every building in Helsinki, as well as the ground surface and waterways. By means of Helsinki’s reality mesh model, it is possible to construct three-dimensional computer views of whichever nook in Helsinki.

– Through the http://kartta.hel.fi/3d/ web service it is possible to download the 3D Helsinki basic data of a chosen building or area in the desired file format.

The digital modelling of the city environment has taken giant leaps over the last few years. The digital model of Helsinki is based on a laser scanning made from a height of 500 meters. The result is a dot cloud, which maps the city structure at a 10 centimetre resolution. When the data is combined with the city’s map and geographic datasets and the information of the registry, it becomes a dimensionally accurate model of the city.

Helsinki has been 3D modelled since the beginning of the 1980’s, but creating a model with current technology is no longer handwork. Helsinki’s semantic CityGML information model was created with quite minimal human efforts. For example, the different surfaces of the buildings are automatically classified as roofs, walls and windows. ICT can also determine by itself if the roof of the building is a mansard roof or a traditional saddle roof. In addition to the buildings, Helsinki’s model includes information about the surface forms and waterways, soon also the city’s bridges and trees.

The model can be used to solve problems which have previously not been solvable.

“We can, for example, ask the model how many windows in this area have a view of the sea”, says Jarmo Suomisto, Project Manager of the 3D project.

Another example of application is the noise modelling of city events. The model could be used, for example, for charting the disturbances of outdoor concerts in advance. At the Ultrahack of spring 2017, Helsinki is looking for easy-to-use solutions for utilising the model in event organisation.

The reality mesh model challenges Apple and Google

“Initially we were just going for a 3D information model, but as we had 50,000 aerial photos of Helsinki at our disposal, we decided to make a mesh model of the city as well”, tells Suomisto.

The reality mesh model can be utilised for many kinds of visualisation needs. Based on the aerial photos shot in summer 2015, the entire surface area of Helsinki and its islands, almost 500 sq. km, can be textured realistically. The digital buildings of the information model can be made to look like their real counterparts, when an aerial photo is “glued” onto their walls and roofs.

Jarmo Suomisto says that the reality mesh model has been created much in the same way as the 3D city models of Google Earth and Apple’s Maps application. Apple’s 3D Helsinki is already quite old data. For example, the Kalasatama area looks quite different in real life than it does in the 3D model running on the Mac screens. On the other hand, Google Earth’s latest Helsinki model looks pretty much the same as Helsinki’s own aerially photographed model from the summer of 2015. There are differences as well.

“Our material is a lot more dimensionally accurate”, says Suomisto.

The dimensional accuracy is of such quality that the user can acquire the data from the City’s server directly to a CAD-programme and start the planning work. For example, event organisers can plan the outlines of the area, the stages, the stalls and the emergency exits directly on the 3D reality mesh model.

Openness is important

From an application developer’s perspective, the city’s material has a superior ace up its sleeve. The information is offered as open data. The basic data of Google’s and Apple’s city information models is firmly stored in their own databases, while the data of the City of Helsinki’s 3D model can be acquired and utilised in totally new ways by anyone.

This is also encouraged by the application developers to whom the models have been presented. An event held in February generated almost 30 ideas about how the world’s most progressive 3D city model could be utilised. An idea was to bring the Helsinki views of the 3D model to the screens of treadmills at gyms. A flood analysis tool based on the model would be able to tell which buildings are first at risk if the sea level rises faster than expected in the future.

The city is working, among other things, on a Helsinki solar energy Atlas, which takes advantage of the 3D city model. It is a web service, which tells the production potential of walls and roofs of the buildings in Helsinki.

The city’s 3D model constructors are eagerly waiting to see if the data yields something revolutionary in the hands of data enthusiasts or software companies, in addition to their own utilisation projects.

Do you want to get your hands on 3D models? Join Ultrahack to make HEL of 3D city happen!

Join Ultrahack Built Environment Track and hack new services for event organizers with City of Helsinki 3D resources. We challenge you to think of visual representations of 3D city models with complementing data sources. What kind of value could they add to event planning, marketing, organizing and participating? It’s your call! Apply ultrahack.org April the 14th latest and have a chance at winning 5000 EUR cash prize. Ultrahack Sprint 1 2017 will be held April 21-23, at Airo Island, Helsinki, Finland.

Original text: Petja Partanen

Also read the article published on the Helsinki Region Infoshare website about the 3D city models event and browse the application ideas of the workshop (in Finnish). http://www.hri.fi/fi/ajankohtaista/helsingin-3d-kaupunkimallit-kayttoon/

Information about Helsinki’s 3D city models www.hel.fi/3D

3D-information model viewing service http://kartta.hel.fi/3d/

The 3D reality mesh model as open data http://www.hri.fi/fi/dataset/helsingin-3d-kaupunkimalli

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