What are the two types of spatial data?
Geographic information systems work with two fundamentally different types of spatial data: the vector model and the raster model. Vector data is well suited for describing discreet features, such as summits or well points, while raster data is well suited for displaying values that change over a larger area, such as elevation data or vegetation. Vector data models information about points, lines, and polygons as a x,y coordinates. The location of a point feature, such as a summit, can be described by a single x,y coordinate. Linear features, such as highways or political boundaries are a series of point coordinates. Polygon features, such as floodplains or lake boundaries are stored as a closed loop of coordinates. Raster data models continuously varying features such as soil type, vegetation, or elevation. A raster image is a collection of grid cells where each cell has a value. The most common example of GIS raster data are hard copy maps or digital orthoimagery. The raster data are
