There are two main categories of geospatial analysis and file types, vector and raster. Vectors are all about shapes, while rasters are more about grids. Vector is more common due to flexibility and efficient storage. Vectors can be defined simply by using a set of points. There are three main types of vector geometry:
- Points: This can be defined in two or three dimensions. It is the common latitude, longitude pair you are probably very familiar with. The airport locations used in the R code previously are examples of points.
- Lines or LineString: A LineString is defined by a set of points and order is important. More than one LineString can be stored together; in that case it is called, unsurprisingly, a MultiLineString. A river system or roadways network is an example of a MultiLineString. A file that contains a MultiLineString for the US Interstate roadways network can be downloaded from the University of Iowa GIS Library (ftp://ftp.igsb.uiowa.edu/gis_library/USA/us_interstates...
