Methods of representing geographic space Raster Model Vector Model
Map as an Abstraction of space: • Spatial features can be represented as points, lines and area(polygons). • Some objects are selected for inclusion and another not spatial feature and it have attributes as 1- simplified 2-aggregated 3- classified. • When the geographies want to enter the data to GIS, they have some decision need to made based upon to can entered it to computer.
The definition: • Raster Models: It is that features made of cells and each cells related with another cells. • Vector Models: It is that features included points, lines and polygons and their data is spaghetti.
Vector Models • It is represent by (x , y) coordinates. • Vector model take less storage. • Example for vector model is digitization. • We take long time when make vector model.
Raster models • It is represent by (pixel or cell) • It is take more storage. • Example for raster model is scanning. • We take short time when make Raster model.
Geographic Representations • CELLS: a representation of geographic data on rows and columns . • PIXELS: a group of points with a color value but no data related to others
Raster and vector representation • Raster representation Vectorrepresentation