Primary data sources. Those that generate data that has to be adapted or converted are called secondary

Printed cartography. Digitization

A large amount of cartography exists in printed form, such as maps or old analogical aerial photographs. To be used in a GIS, this cartography has to be digitized, which means creating raster or vector layers from them. In this latter case it also implies separating the different types of infor- mation that the map might contain, since the information in a single printed map would be stored in independent layers, in GIS

Digitizing a printed cartographic document involves three steps:

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  Georeferencing the original document. That is, set- ting a geographical context (coordinate system, control points, etc.), so the digitized elements produced are cor- rectly referenced.
  
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