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Introduction to GIS: Basic Concepts

United Nations Economic Commission for Africa (UNECA)

ICT and Sciences & Technology Division (ISTD)

Aster Denekew Yilma

Geographic Information Systems Officer

e-Applications Section, ISTD

TOT for Media on Geospatial Science and Technologies17-18 September 2012


Introduction to GISGeospatial Technology also known as Geomatics is the technology used for gathering, storing, processing, and delivering geographic/spatial informationGeospatial technology includes: geographic information systems (GIS), cartography, remote sensing, land surveying, global navigation satellite systems (GPS, GLONASS, Galileo, Compass), photogrammetry, geography and related forms of mapping.


Introduction to GISWhati is GIS?

A Geographic Information System (GIS): is a system that integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information

Geographic Information Systems are Information Systems which are extended to handle geographic data/ spatial data. Gives better picture and understanding of the real-world


Introduction to GISOrganizations use GIS to solve problems and improve processesGIS benefits organizations and individuals in many ways:

Increased Efficiency; Cost Savings; Improved Communication; Better Decision Making; etc.


Components of GIS GIS integrates the five key components

GIS software and hardwareDataPeoplePolicy and procedures


Components of GISThe hardware is the computer on which the GIS operate.

It includes the associated hardware used for data capturing, and dissemination, for example: GPS, digitizers, Scanners, Printers, plotters, etc.

GIS software provides the functions and tools needed to store, analyze, and display geographic data/information


Components of GISData is important part of a GIS The most expensive component of a GIS.

due to the high costs of data acquisition, especially using remotely sensing earth observation satellites.

Building the database also takes a lot of time, and large amount of money. Implementing a GIS database requires planning and choosing the right information base for the particular application of an organization/business.


Components of GISThe people: who makes it possible to enter, manipulate, interpret, analyze and present the geogrphic/(geo)spatial data in a form usable by every one, the geospatial information. GIS is an interdisciplinary field that requires varied backgrounds of expertise (the people) depending on the applications in use


Components of GISInstitutional frameworks and policies are also important for a functional GIS.

The interest and willingness of decision makers to exploit GIS technology, and The organizational setup for collecting spatial data, analyzing,and using the results for planning and implementation

Procedures refer to the way people do their jobs and the changes they will have to make using the GIS system.


Basic GIS Functionalities Four main Functions:

Data capture (e.g. data entry, scanning, digitizing,)Data manipulation (e.g. editing, data conversion, data integration, etc.)Data analysis Data presentation and output (e.g. map making, printing, etc.)


Basic GIS FunctionalitiesGIS maps are interactive: map users can scan a GIS map in any direction, zoom in or out, change the level of details, the nature of the information visualized in the map, etc.Spatial queries based on spatial location(selecting spatial objects for example, countries, or cities in a map )Spatial data analysis capabilities: tools to perform GIS analysis


Basic GIS Functionalities

Navigation Tools


Basic GIS FunctionalitiesThe presentation functionality makes GIS unique. GIS visualizes Maps, images and charts, and results of analysis. Visualization outputs can be printed/exported in a format suitable to be shared.


Geo-Spatial DataAwareness towards the importance of having access to reliable, timely and affordable geospatial data The right information available at the right time at the right place to take adequate decisionsNeed for Geospatial data/information


Geo-Spatial DataSpatial data is raw data distinguished by the presence of a geographic elementGeographic data, and spatial data /“geospatial data” used interchangeably Geographic information, Geo-information, spatial informationInformation resulting from interpretation of geospatial data


Geo-Spatial DataTwo components of geospatial data: geographic position and attributes/ propertiesGeographic position answers “where is it” - referred as spatial data

the location of a geographic feature or phenomenon (x, y, z)

Attributes answers “what is it?” – attribute/non spatial dataGIS stores geospatial data, with its attribute information in a GIS databaseProvides link between the geographic position/spatial data and attribute data/non-spatial data


Geospatial Data SourcesGeospatial data acquired using different sourcesData acquisition is the process of acquiring data using different techniquesData capture is the process of putting the data into the systemData sources are sources that can be used for capturing and creating spatial data in GIS


Geospatial Data SourcesCommon data sources:

Paper maps, Aerial photographsGPS (Global Positioning Systems) Surveying instruments, e.g. Total StationImageries from Remote-sensing satellites/ Earth observation satellites and Laser Scanners, usually mounted in AircraftsExisting digital data


Geospatial Data SourcesData Acquisition using Remote Sensing Satellites/Earth

Observation Satellites:Remote sensing is the art, science and technology of observing

an object, scene or phenomenon by instrument based technique.“remote” - the observation is done at a distance with out

physical contact

Earth observation is gathering of information about the planet earthEarth observation satellites are satellites specifically designed to observe Earth from spaceEarth Observation satellites provides us geospatial data


Geospatial Data SourcesEarth observation satellites are sources of huge amount of data Data from Earth observation satellites/ Remote sensing satellites are processed into images: remote sensing images, satellite imageries andsatellite data


Geospatial Data SourcesExamples of Earth Observation satellites for data sources:

NOAA, LANDSAT, SPOT, RADARSAT, IRS, QuickBird, GeoEye (IKONOS, GeoEye I)NigeriaSat, and SambandilaSat, etc.


Geospatial Data SourcesData Collection using GPS

Global Positioning Systems (GPS) used for data collection and capture Global Positioning System is a space-based satellite navigation system that provides location and time information Data collected using GPS can be imported in to a GIS system


Geospatial Data SourcesSecondary Sources /Existing Data

Most GIS databases created with data converted from paper form/Aerial photoFeatures extracted from satellite images using image processing techniques, and already existing in different databasesExisting digital data are available in different formats


Geospatial Data SourcesExisting Data

Digital maps, datasets and image data are available in the Internet, in different data portalsWe can make use of such resources with little or no cost


Thank you!

Email: [email protected]

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