2.2. GIS framework

The main principles of GIS (geometric properties, attributes, and topology) are built into two data structures: vector (e.g. points, lines, and polygons) and raster (e.g. climatic, altitude, or satellite imagery). The terms “layer” or “dataset” are used to denote a raster or a vector file type that contains a similar theme, for example, varying elevations across a terrain or locations of honey bee colonies, respectively. It is possible to convert a raster layer to a vector layer and vice versa, depending on what type of analysis will be conducted with the data. Each layer contains information about its geometric properties and a table of attributes associated to and linked with, its respective geometric properties (Fig. 1). You can view each layer’s properties in GIS to see the resolution, file type, size of the file, and other information of importance.

Fig. 1. The GIS data framework is made up of both geometric properties and attributes associated with the geometry. A row in the attribute table exists for every polygon on the map. Some of the attributes for this Swiss layer include the names of cantons and their abbreviations, the country code, the country name and abbreviation, and the area. Reproduced with permission of Swisstopo (BA13016).


2.2.2 Raster data structure