Representing Data with Raster and Vector Mode

Raster Model

  • Area is covered by grid with (usually) equal - sized, square cells
  • Attributes are recorded by assigning each cell a single value based on the majority featured (attribute) in the cell, such as land use type.
  • Image data is a special case of raster data in which the "attribute" is a reflectance value from the geomagnetic spectrum
                           - cells in image data often called pixels (picture elements)

Vector Model
The fundamental concept of vector GIS is that all geographic features in the real work can be represented either as:
  • points or dots (nodes): trees, poles, fire plugs, airports, cities
  • lines (arcs): streams, streets, sewers
  • areas (polygons): land parcels, cities, countries, forest, rock type
Because representation depends on shape, Mapview refers ro files containing vector as shapefiles