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Blog: Should we share spatial data on the web?

Frans Knibbe’s blog Should we share spatial data on the web?

Spatial data on the web offers unprecedented opportunities. It’s an indispensable ingredient in concepts such as Big Data, the Internet of Things, Machine Learning, and smart living environments, but we still have a way to go before they can be used properly. To this end, the Spatial Data on the Web Working Group (SDDWG) was set up in 2014.

Frans Knibbe (Geodan Research) considers the value of spatial data sharing on the web, as well as showing why collaboration within the domains of spatial data and the web is necessary.

What exactly is the web?

In everyday language, the Internet and the worldwide web (www) are often interchangeable concepts, but there are clear differences between the two. Born from a predecessor from 1969, the Internet as we know it started in 1983. The basis of the internet is TCP/IP, a standard for communication between computers. The existence of the internet enabled the creation of the worldwide web (www or simply 'the web').

The web started in 1991 and was invented by Tim Berners-Lee, now director of the W3C. The web cannot exist without the internet; it’s one of the applications that run on the internet (email is an example of another application). The web itself is also based on standards. The most important are HTTP - a protocol for the exchange of hypertext (text with hyperlinks, like this blog), HTML - a standard format for the layout of hypertext, and the URL or URI - a universal resource identifier.

The creation of the web made it possible to publish and link text documents in a universal way. In addition to text, (silent or moving) images were later shared via web standards as well, and nowadays, web browsers can do so much that they can be regarded as fully-fledged operating systems (such as Windows or Linux). That the web has had a huge impact on the world is almost an understatement. Worldwide communication has changed drastically and the web has also prompted radical social, economic, cultural, and political change. The web itself, however, is also changing. There is a growing tendency to use the web for sharing raw data, which is a source of information and knowledge. It forms the foundation of many decisions made by companies, authorities, and citizens.



“The web cannot exist without the internet; it’s one of the applications that run on the internet.”

Frans Knibbe

Spatial data: more than just geo-data

Data that says something about location is spatial data, and that includes more than just the geographic data traditionally stored and used by Geographic Information Systems (GIS). To begin with, it’s good to realize that the term 'spatial' is more general than 'geographical'. Geographical data uses the earth, or a model of the earth, as a reference. Data about locations on other celestial bodies is therefore spatial, but not geographic. Data about locations that are on earth, but do not use a coordinate system that is related to the earth, is also spatial but not geographic.

Take, for example, 3D models of buildings, which often use a coordinate system that is not directly related to the earth. Another form of spatial data was mentioned in one of the use cases for the SDWWG: the description of shapes and spatial relations in microscope images, for the benefit of cancer research. Spatial data is therefore not limited to the human scale.

On top of that, it’s good to realize that spatial data isn’t restricted to being expressed in numbers (coordinates). There are also other ways of indicating locations: for example via names (toponyms) or addresses.

Finally, data exists about places with an unknown or vague location. If you know something about history, or if you’ve read "Asterix and the Iron Shield," the place name Alesia may sound familiar to you. It’s a historic place, but we haven’t been able to agree on its exact location yet.

Another form of vagueness occurs in contemporary concepts such as 'the Middle East', 'the Sahara' or 'the Randstad’: it’s impossible to give a good definition of where these areas begin and end. However, they are spatial objects nonetheless. How about 'across the street' or 'in my left pocket'? They, too, are location determinations. The last two examples also indicate that spatial data is comprised of more than records of locations. Relations between locations are also important and can be recorded as data or derived from location determinations. Examples include: 'Belgium borders the Netherlands' or 'I am twenty kilometers from the nearest gas station'.

Taking a holistic approach can be fruitful

Historically, developments in spatial data and web data have taken place in separate domains, but fortunately, there is now a trend of mutual rapprochement. Take, for example, the increasing popularity of specifications such as GeoJSON (vector geometry in JavaScript Object Notation) and TopoJSON (an extension on GeoJSON that stores geometry topologically), or the ever-evolving development of what Google does with geographic data. However, many developments still take place within the separate domains. That’s a shame, because by approaching problems as holistically as possible, we can make the most sustainable progress.

From a historical GIS perspective, there is a desire for economies of scale and increasing interoperability (better exchange of data between various digital systems). First-generation GIS was characterized by data storage in files and formats that differed per GIS package. Interoperability was low; to use data from one package in another, you had to convert the data, with all the hassle and risks involved. With second-generation GIS, you could store geographic data in more general relational databases, which allowed for the use of larger quantities of data. In the meantime, several types of software could use the data and you could better combine geographical data with other types of data. And now, we are all set for third-generation GIS, where all data, spatial and non-spatial, is shared via one large, globally distributed database. Here, most user interaction will take place via web applications, representing another big step forward in terms of scale and interoperability.

Knowledge is urgently needed

The increasing importance of raw data can be seen from a historical web perspective: the web is developing from a platform to share documents into a comprehensive IT system, which requires a way to store, share, combine and query raw data. With this development, the knowledge about spatial data that has been built up in the GIS world over the past decades is indispensable. In order to work with complex objects, coordinate systems, spatial relations, spatial networks and the like properly, the knowledge that has been built up within organizations such as the OGC is urgently needed. We will have to make the most of all this knowledge.


In summary, it’s very important that spatial data work well on the web. In order to realize this, the Spatial Data on the Web Working Group (SDDWG) was set up, a joint initiative of the OGC and the W3C. 


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