Marmota : OpenStreetMap overlay

OpenStreetMap overlay

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OpenStreetMap overlay

Until just a few weeks ago, we used only a single ‘peak names’ source: geonames.org. It is a global collection of toponyms created and updated by the community in a wiki style. Each toponym in geonames is a point, characterized by its geographical position and class. This is ideal for labelling peaks, but it is very limiting when dealing with spatial features, like rivers, lakes, roads, boundaries, etc.

To overcome this limitation, we decided to explore the more advanced data coming from OpenStreetMap. OpenStreetMap is “a free editable map of the whole world” that can be seen as a huge collection of geographical elements. There are three types of elements: nodes, ways, and relations. Nodes are just geospacial points, like geonames’s toponyms. A way is an ordered interconnection of nodes that describe a linear feature such as a street, or similar. A relation can group other elements together, nodes, ways, and even other relations. Instead of the static node classification of geonames, in OpenStreetMap each element is associated with a number of key-value pairs (tags) describing the element.

Today’s picture was taken by Michele Zanin from a panoramic viewpoint near to the village of Fai della Paganella, looking South towards Trento, Italy. The peak names come from geonames, while rivers and the motorway are from OpenStreetMap. This is just a first example of an OpenStreetMap overlay; we plan to explore more deeply this kind of data visualization in the near future.

During the first Italian OpenStreetMap Conference (5-6 June 2009) OSMit, we met Steve Coast, the guy that started the OpenStreetMap project in 2004. He wrote a post on his blog about us, using today’s image as an example.

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