2. introduction to gis (geographical information system)

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Introduction to GISIntroduction to GIS(Geographical Information(Geographical Information

System)System)



What Is a GIS?What Is a GIS?

A geographic information system (GIS) isA geographic information system (GIS) isa computera computer--based tool for mapping andbased tool for mapping andanalyzing things that exist and events thatanalyzing things that exist and events that

happen on earth.happen on earth. GIS technology integrates commonGIS technology integrates common

database operations such as query anddatabase operations such as query andstatistical analysis with the uniquestatistical analysis with the uniquevisualization and geographic analysisvisualization and geographic analysisbenefits offered by maps.benefits offered by maps.



GIS DefinitionGIS Definition

Burrough (1986) defines GIS asBurrough (1986) defines GIS as ³a set of tools for ³a set of tools for collecting, storing, retrieving at will, transformingcollecting, storing, retrieving at will, transformingand displaying spatial data from the real world and displaying spatial data from the real world for a particular set of purposes´ for a particular set of purposes´

Aronoff (1989) gives a. general description of GISAronoff (1989) gives a. general description of GISasas ³any manual or computer ³any manual or computer--based set of based set of procedures used to store and manipulate procedures used to store and manipulategeographically geographically--referenced data.´ referenced data.´

More specifically, Aronoff (1989) defines GIS asMore specifically, Aronoff (1989) defines GIS as aacomputer computer--based system that provides four sets of based system that provides four sets of capabilities to handle georeferenced Data: 1.capabilities to handle georeferenced Data: 1.Data input 2.Data management (Data StorageData input 2.Data management (Data Storageand Retrieval), 3. Manipulation and analysis, 4.and Retrieval), 3. Manipulation and analysis, 4.Data Output Data Output



The major challenges we face inthe world today--overpopulation, pollution,deforestation, natural disasters--have a critical geographicdimension.



Gis ConceptGis Concept



Evolution of GISEvolution of GIS

Revolution in information technology Revolution in information technology

Computer TechnologyComputer Technology

Remote SensingRemote Sensing

Global Positioning System (GPS)Global Positioning System (GPS)

Communication TechnologyCommunication Technology

Rapidly declining cost of computer Rapidly declining cost of computer

hardwarehardware

Enhanced Functionality of softwareEnhanced Functionality of software



Why GIS?Why GIS?

70% of the information includes some70% of the information includes somegeographical Facts in the decisiongeographical Facts in the decision--making processmaking process

Ability to assimilate divergent sources of Ability to assimilate divergent sources of data both spatial and nondata both spatial and non--spatialspatial(attribute data)(attribute data)

Visualization impactVisualization impact

Sharing of informationSharing of information

Analytical capability in a spatial contextAnalytical capability in a spatial context



Spatial OperationsSpatial Operations

Many computer programs can handleM

any computer programs can handlegeographic data such as those describedgeographic data such as those describedbelowbelow

1.1.Spreadsheets (e.g., lotus 1Spreadsheets (e.g., lotus 1 --22--3,3,QuatroPro).QuatroPro).

2.2.Database Management SystemsDatabase Management Systems(e.g., Oracle, dBase)(e.g., Oracle, dBase)

3.3.Computer Aided Design (e.g.,Computer Aided Design (e.g.,AutoCad)AutoCad)

4.4.Cartographic packages (e.g. AldusCartographic packages (e.g. AldusFreehand, CarthoGraphix)Freehand, CarthoGraphix)

5.5.Photogrammetrical software (e.g.Photogrammetrical software (e.g.DMS)DMS)

6.6.Image Processing Software (e.g.,Image Processing Software (e.g.,

ERDAS)ERDAS)



Geometry and attributes of Spatialobjects

Points, Its ID and Attributes

Lines, Its IDs and AttributesPolygons, Its IDs and Attibutes



Perform Geographic QueriesPerform Geographic Queriesand Analysisand Analysis

Improve OrganizationalImprove OrganizationalIntegrationIntegration

Make Better DecisionsMake Better Decisions

Making

Maps

Making

Maps

What Can GIS Do for You?What Can GIS Do for You?



Component of GISComponent of GIS

HardwareHardwareSoftwareSoftware

DatabaseDatabase

People (Users)People (Users)

Methods (Policy and ProceduresMethods (Policy and Procedures



How GIS Works ?How GIS Works ?

1.1. Geographic ReferencesGeographic References

2.2. Vector and Raster ModelsVector and Raster Models



GIS TasksGIS Tasks

InputInput

ManipulationManipulation

ManagementManagementQuery and AnalysisQuery and Analysis

VisualizationVisualization



Proximity AnalysisProximity Analysis

Overlay AnalysisOverlay Analysis



Data for GISData for GIS

What Map Data Do I Need?What Map Data Do I Need?

±±Base MapsBase Maps

±±

BusinessM

aps and DataBusinessM

aps and Data±±EnvironmentalMaps and DataEnvironmentalMaps and Data

±±General Reference MapsGeneral Reference Maps



How Do I Get Map Data?How Do I Get Map Data?

Methods In NepalMethods In Nepal

±± Existing mapsExisting maps

±±

Field SurveyField Survey±± Digital data available inDigital data available in

Departments of Survey, MinDepartments of Survey, MinBhawan, Kathmandu, NepalBhawan, Kathmandu, Nepal

±±ICIMODICIMOD

2. introduction to gis (geographical information system)

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