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Data Classroom



Data Types and Models
Spatial Data Spatial data includes points, lines and areas. Points represent anything that can be described as an x, y location on the face of the earth, such as shopping centers, customers, utility poles, banks, and physicians' offices. Lines represent anything having a length, such as streets, highways, and rivers. Areas, or polygons, describe anything having boundaries, whether natural, political or administrative, such as the boundaries of countries, states, cities, census tracts, postal zones, and market areas. The spatial data described above is one of two models used to represent data in a GIS. It is called a vector model. With a vector model, each feature is defined by x, y locations in space (the GIS connects the dots to draw lines and outlines, creating lines and areas). Another model is the raster model. With the raster model, features are represented as a matrix of cells in continuous space. A point is one cell, a line is a continuous row of cells, and an area is represented as continuous touching cells. Raster or Vector? While any feature type can be represented using either model, discrete features, such as customer locations, pole locations or others, and data summarized by area such as postal code areas or lakes, are usually represented using the vector model. Continuous categories, such as soil type, rainfall, or elevation, are represented as either vector or raster.

GIS Map 1
Description of the Map

GIS Map 2
Description of the Map

GIS Map 3
Description of the Map
www.rain.org/gis