Abstract

It has been widely recognized that gathering data accounts for more than 80 per cent of the cost of any GIS project. Software and hardware costs are decreasing, but not datasets. In the analog era, unauthorized copy of the datasets was difficult to made, requiring not only access to them but also specialized equipment and procedures. Fast Internet connections and digital datasets threaten the data producer investments through piracy, which today is easier than ever. Software providers have solved the piracy problem for their product supplying hardware keys, or through runtime license services. However, they do not offer similar protection to the dataset being used by their software. Reasons are both technical and legal. Outside the GIS community this problem has been known for a long time; we will consider current, possible solutions for digital imagery, formatted text, 3D meshes and so on, showing possible links to typical Geospatial datasets. The current proposed solution forces the data producer to rely in weaker protection means: the dataset delivered to customers is functionally valid, but some subtle changes identify uniquely the buyer, the supplier as well as other extra information. The process for embedding hidden information in a dataset without producing perceptible changes is denoted as watermarking. The producer can recover the embedded information on request in order to produce evidence of ownership in a court, so the overall strategy relies on legal basis rather than technical ones. The differences with cryptography will be made clear. This paper analyzes the state-of-the-art for watermarking protection in digital geographic datasets, with emphasis to the technical aspects. We analyzed the situation of some typical formats: raster images, vector and point datasets, as well as text and databases. Some reference to the legal status of copyright digital geographic data in the US and the EU is also presented. The review makes evident that digital imagery has clearly a maturer situation, even with multiple commercial vendors offering watermarking protection. 2D vector and point datasets have received less attention from the research community; however, 3D meshes have been considered by the CAD community and a handful of techniques are available for that case, and they are reviewed here. Some references are provided for the case of text and databases.

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