Topography as a platform for smart cities and design


With the Key Registry of Large-Scale Topography, The Netherlands has a nationwide ground plate suitable for sharing digital constructions, 3D data generated through smart cities and Artificial Intelligence-fed self-learning applications.

The Netherlands is a European Union country spread across 41,500 square kilometers, with a population of around 17 million. The country is featured among the top 10 functioning economies, and has numerous spatial policies in place. These policies ensure that the Netherlands secures a high position on the Countries Geospatial Readiness Index (CGRI). A lot of work is currently being done on the creation of a Digital Environmental and Spatial Act, and this, along with other policies float to a large extent on numerous key registries. One of these is the Key Registry for Large-Scale Topography (BGT). As many as 392 source holders are responsible for the nationwide digital topographic map, each with their own GIS department. Nearly 2000-5000 employees are involved in BGT directly or indirectly.

BGT background

The object-oriented BGT is based on an earlier digital file: the line oriented base map (GBKN). This was a CAD drawing of all the streets, buildings and waterways of the country. The conversion of GBKN into a collection of objects, polygons and points ‘with added intelligence’ took place between 2010 and 2016. During the construction of this huge map file, 44.5 million objects were added in four years, of which several millions were locating points. With 40,000 changes each day, the current contributions from source holders have become the basis for a living document. BGT now receives around 250,000 online hits each day.

Single spot of truth

Behind the creation of BGT, one finds the ultimate form of cooperation in map making. “One of the biggest changes in thinking about a nationwide base map was the introduction of ‘confidence’. There should be confidence that the borders of the other parties, your ‘neighbors’ if you will, are correct. That was a huge turnaround,” says Jan Bruijn, Director of Collaboration Platform SVB-BGT. SVB-BGT is responsible for the greater scale topographic map of the Netherlands. The secret behind the national success of BGT is the merging of different regions. Bruijn explains: “Hundreds of municipalities, more than 20 water boards and 12 provinces work together in this, other stakeholders join in. We now work with 21 regions. These source holders are maintaining the system collectively. The perceived truth in their map is no longer situated in their own management area. The ‘single spot of truth’ for all users is now residing in the National Supply. It has become a new way of working. To form the initial map, each source holder did an initial delivery.”


The desired topicality of BGT is six months for buildings and roads; for rural areas it is set at 18 months. Although it is important to keep track of how often, and on which scale, a source holder distributes changes to the National Supply, a general maxim has come to the surface. According to Bruijn: “When more than 10% of your data has changed, the current situation is usually alright. However, if you see a totally different number come up, it’s advisable to check internally whether that figure is correct. There may of course have been major changes to the map, but it may also be that changes have not been passed on properly, or might not have been passed on at all.”

Topography for smart cities
Asset management, road features in Rotterdam

Transactional system in Oracle

Oracle specialists from Dutch IT service provider, Transfer Solutions, designed a source holder portal called BRAVO. “At Transfer Solutions, they have come up with something very clever within Oracle,” says Bruijn. “The reason that we can work nationwide at the current speed lies in the database. It is not ‘normalized’ conform the standard object model of BGT, specified by standardization organization Geonovum. To us, every object has its unique code. There is nothing more to it. So, all the objects are placed on one single table, a simple but very effective implementation to reach an acceptable performance level.” The system is mainly concerned with a massive receipt and transmission of changes through check-in and check-out. “It is enormously successful. And above all, the BRAVO portal, the place every source holder logs in to. It is just a transactional system. No more, no less. Its workings are not related to any geospatial or CAD tool. That has been a very good decision,” Bruijn adds.

Topography for smart cities
Population per building. Data courtesy of key registry on persons Buildings and their age (red to blue/ old to new). Year of construction courtesy of BAG key registry

Dynamics of the chain

The questions that arose during the design of the message service to be set up were discussed with the stakeholders. Solutions were tested in practice by a group of ‘frontrunners’. Bruijn has fond memories to share from that pioneering phase. “From the very beginning, there was intensive contact between stakeholders and software suppliers. Some of the municipalities that were at the forefront of technology, such as Rotterdam, Leiden, Valkenswaard and a couple of water boards and provinces, were the first to provide their geodata. In all those cities, different software suppliers worked on the message service.” Thanks to these frontrunners, a working standard could be defined early on. “We not only wanted to get the most out of technology, but also wanted to draw up a sound set of rules and consult constructively with stakeholders. A methodology was drawn up on which comments could be given. And then, it became final,” says Bruijn.

Dormant conflicts

In the compilation of a national file with regional contributions, continual dormant conflicts threatened to surface. Jan Bruijn looks back on these with empathy. “You can imagine, for example, smaller municipalities quickly calling out that they cannot handle it,” he says. In order to meet this challenge, a subsidy system was chosen in which funds are divided per municipal ‘assembly’. Such an assembly consists of all components of all source holders who collectively make a fully filled BGT file. “Think of a municipality that supplied data, including data from the Water Board, the Ministry of Agriculture, Nature and Food Quality (LNV) and the province. This municipality would receive a subsidy,” Bruijn adds. SVB-BGT itself has a limited budget. According to Bruijn, the Dutch municipalities have made the largest investment and their suppliers have aligned it.

Topography for smart cities
Original key registry 2D topography as presented in public BGT data set

Investments in BGT

Although the nationwide key registry has been in place since 2016, investments are still being made in BGT. Jan Bruijn, however, shows himself cautiously: “Of course, improving BGT can always go ahead, and we must not forget the user of this nationwide service. At the same time, however, we will need to capitalize on what we have built,” he explains. The next step is to realize an integrated geospatial platform. Bruijn feels the current situation is as follows: “Part of the tasks of the GIS specialists currently consists of combining data sets. That will all fall away if we really start working integrally. A ‘single point of truth’ will arise where all information can be found. BGT should be the reference for this. It is the logical basis on which other government information can be accessed.” There already is a national portal that functions as an online entry for, among other things, the key registries. PDOK (Public Data On Map) consists of around 50 services that can all be viewed in separate viewers. Alas, in practice, PDOK appears to be rather limited in use. “It’s too specialized in nature,” says Bruijn.

Topography for smart cities
The goal: a healthy ecosystem in which good data quality and robust interdependence make for a great data platform


The feedback system is a core value of the existing basic registrations in the Netherlands. Errors are reported by users and stakeholders. For example, the online publication of public data ensures cleanup and quality improvement. For several key registries, there is currently an integral feedback to the source holder. This fact will continue to play an important role in the future use of basic registrations. Jan Bruijn is looking forward to it. “With all the data in an integral viewer, you are guaranteed to get more questions. It is therefore good to be able to overcome all this with a validation system that works automatically, for example with Artificial Intelligence. We have to make it into a learning system,” he says.

Need for integral development

At this moment, the geo-related key registries in the Netherlands are useful and are frequently used instruments in themselves. They are being deployed for numerous processes both within and outside the government. They thus form an attractive foundation for a national geo-information infrastructure (NGII). But can they be further improved upon? “It is important to further develop the geo-basic registrations in the NGII. But we need to do it step by step. The substantive and technical efforts that this requires will only yield more social returns and will be realized more efficiently if this is done in full conjunction,” says Hans Tijl, Director, Geo at the Ministry of the Interior and Kingdom Relations (BZK).

Continuous development in coherence

At the beginning of 2019, the Ministry of BZK took the initiative to tackle various developments in this area under the name ‘Continuous Development in Coherence’ (DIS-GEO). Presently, the registries on addresses and buildings, topography and cadaster are still separate key registries. Each has a function of its own. Hans Tijl says: “We want to combine the individual functionalities to increase uniformity, but also topicality and ease of data collection.” An important step taken by the DIS-GEO initiative is the development of a coherent object registration. A coherent object registration is one centrally organized uniform registration containing basic data about objects in physical reality. This means: objects that are visible in the terrain, such as buildings, roads, water, railway lines and trees, parts of the terrain, supplemented with a couple of (administrative) objects such as residences, municipal boundaries and public spaces.

Topography as a Digital Twin

Tijl anticipates that in the future, the Key Registry for Large-Scale Topography (BGT) will form the basis for a Digital Twin of the entire Netherlands. “Such a country-wide model should not only be executed in 3D. We are also thinking about the most usable level of detail. We are in the brainstorming phase concerning level of detail 2 (LOD2), which also includes interior spaces. This would be useful for determining taxes or the valuation of immovable property. The identification of separate apartments within one building will also add to the quality and usability of another basic registration: that of the addresses and buildings (BAG). End users of BAG are, for example, the emergency services, including the fire brigade.”

Area and Environment Server

One of the innovative initiatives to get more out of the key registries is the Area and Environment Server. Behind this 3D map server, we find an illustrious company of people. Jan-Willem van Aalst is well known in the Netherlands as a quirky but effective cartographer who makes optimal use of open data sources. Frank Steggink has a long track record in the field of software development in the geo-world. Matty Lakerveld is also a true geo-IT veteran. He surprised friends and foes before with integrated web-based geo-ICT concepts that, to the astonishment of many, turned out to work and perform well. The Area and Environment Server is also web-based. This data service does not need any specialized or professional software. “Streaming data without a GIS package”, is how Lakerveld summarizes it. The presented combination of data can be used directly in the browser for anyone with an Internet connection. “You see integrated source data from the government at object level,” says Lakerveld with pride.

Good performance in the browser

Lakerveld explains that the 3D visualizations in the Area and Environment Server are not an end in itself; the power lies in combining data sources. “Our Area and Environment Server is looking great, don’t get me wrong. However, for us, the insightful presentation of spatial policy information is much more important than a slick 3D representation. In the end, it’s about good performance. And we wish to give users more convenience. To reach the level that we have achieved now, well, that’s complex enough. After all, we are talking about a combined data set of 2.5 TB. The more bells and whistles you add, the slower the 3D card will render a picture. ” The server does not only show all the key registries with a location element to it. For example, also energy labels of houses, plan topography, childcare and risk maps are included. Especially striking are the publicly available, underground cables from regional network operator Enexis. “The Area and Environment Server is the open data platform on which a growing and ongoing Digital Twin of the Netherlands can be seen in 3D. But the real added value is that users only get to see what they need at a certain location. Up-to-date and reliable information at any time, simply shown either in their GIS package, a geo-viewer, BI tools, Apps or a browser,” adds Lakerveld.

Future insight and Nederland in 3D

Developing a 3D Digital Twin is an important theme and an opportunity for governments. Capturing reality in 3D gives a lot of insight and creates understanding so that better decisions can be made. Dutch company Future Insight supports governments in professionally organizing their own 3D Digital Twin. They already support the cities of Rotterdam and the Hague. This is done using open standards from a central database. In this way, the model is scalable, maintainable, easy to view online and downloadable in all kinds of file formats to use in generic 3D tools. In addition, applications can easily be connected to the available 3D data. Future Insight helps users build the data step by step and ensures that they can be managed and reused in various applications.

Growing step by step in 3D

“We see the construction of a 3D Digital Twin and the implementation of its use as a growth process,” says Rick Klooster, Founder and CCO of Future Insight. “We understand that you will have to start from the beginning. Municipalities can join us with a simple package containing support and training. It is great to see how much added value you can already create by implementing a simple 3D viewer with a combination of external open and your own 3D data with a planning function. Of course, it is great that in the Netherlands there is already so much geospatial data of high quality available, like BGT. Because it makes it really easy to create standard 3D base layers for your Digital Twin.” Klooster knows what it’s like to be at the start of a new development. Ten years ago, he stood at the cradle of an interactive 3D project in the municipality of Apeldoorn. In that city, communication with citizens was made possible in a 3D city model for most projects. There, citizens could walk around virtually and comment on a live feed, using their own avatar. Some current examples in the Future Insight viewer are still in an experimental phase. This means that the performance may vary. “Our viewer is constantly evolving. New examples are constantly being added. The list of applications is endless. Consider, for example, the use of 3D for the environmental law, the energy transition and climate adaptation,” says Klooster.


Please enter your comment!
Please enter your name here