Geographic information system

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GIS
Geographic Information System

INTRODUCTION



GIS= Integrated system that store, manage and analyze geographically located data that you can visualize on a map.
Layer based geographicinformation model.

Features


• •

Points
Lines Polygons

Attributes

http://training.esri.com/Courses/StartGIS/index.cfm

SCALE



Scale is the relationship between the sizeof a feature on a map and its actual size in the real world.
Ratio = 1: 10,000

COORDINATE SYSTEM

• •

The positions of objects on the earth’s spherical surface are measured in geographiccoordinates.
Latitude – longitude: locate exact position on the surface, but they are not uniform units of measure. 1° longitude Equator = 111.321 km., 60° latitude = 55.802 km.

PROJECTEDCOORDINATE SYSTEMS

• •

Data is often transformed from three dimensional geographic coordinates to two dimensional projected coordinates.
Flattening the earth will cause some distortions (Distance,area, shape, direction). Scale

GEOGRAPHIC DATA
Vector data
• • Use shapes to represent features (trees, roads, lakes) Represent continuous data (does not have distinct boundaries or well definedshapes).

Raster data •
• •

Cell structure (arranged in rows and columns) the same size.
Each cell in a raster stores a value. Examples = ground cover, precipitation, DEM.

APLICATIONS
ARCMAP• Display and explore GIS datasets for your study area.

ARCCATALOG • • Browse and find geographic information Record, view, and manage metadata



Define, export, and import geodatabase datamodels and datasets

ARCTOOLBOX
• Access to advanced geoprocessing tools.

GLOBAL POSITIONING SYSTEM (GPS)



GPS tells us the "where". GIS tells us the "what".
24 satellites orbiting theearth at altitudes of approximately 11,000 miles

GPS
• • • • A receiver receives a signal from a GPS satellite It calculates the difference from the current time and the time sent by the...
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