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‘Cartographic generalisation should be automated’

Switzerland: Contrary to common belief in the past, critical parts of the map production process, including cartographic generalisation, can be automated to produce quality results. This saves valuable time and resources, according to an article published in ‘Geomatik Schweiz‘ (May 2010). In this article, Dipl. natw. ETH Dominik Käuferle, Head of Engineering Cartography, the Swiss Federal Office of Topography, swisstopo, talks with facts and figures about how Axes Systems is achieving excellent results using the automatic generalisation.

According to the article, the national maps of Switzerland are high-quality topographic maps at 1:25000 to 1:1 000 000 scales. In order to satisfy the ever-increasing demand for vector GIS data, the Federal Office of Topography swisstopo is working on changes to their production process ranging from the compilation of topographic base data to the production of maps.

Once the data is available in a cartographic source model, generalisation – the automation step most important from a cartography point of view – takes place in the system “SysDab”. SysDab is being developed within the framework of the project OPTINA-LK by Axes Systems AG and is based on axpand, a data-based cartographic GIS system. SysDab is responsible for the fully automatic generalisation of the source model. Generalisation, alongside text placement, is the core of cartography.

Generalisation is concerned with making maps readable in spite of limited space in which to display the data. Where necessary, important elements are emphasised and less important elements are simplified or eliminated. For a long time generalisation was considered to be a step that could not be automated. Cartographers require a four-year professional education and significant professional experience in order to learn how to manually generalise the various topographic map scales.

SysDab fulfilled this goal. Recent tests using mid-land map sheets showed that and average of 80% of the objects in the DCM25 were correctly automatically generalised according to generalisation rules. An important element is an excellent building generalisation during which complex forms are simplified and objects are aligned to each other, as well as a number of other well-functioning generalisation operators. There is potential to further improve the automatic generalisation in SysDab for the DCM25.

This way, cartographers can concentrate on more complex challenges that still require know-how, intuition and a trained eye. Cartographers will not be replaced by automation since data-base supported GIS cartography is extremely know-how intensive. The job description of cartographers will change, however, and new knowledge will be required.

Source: Axes System