Geographic Information Systems
& Map Projections
What Is GIS?
● Geographic – place on Earth, Spatial – Where something is on earth?
● Information – data (facts) put together (layering) to make sense e.g. the number of people using a
road. Data used in GIS can be the following: Maps, Remote sensing, Spatial resolution, Spectral
resolution
● System – interrelated information – Using the data to make it mean something.
Definition:
GIS is an organized collection of computer hardware, software, geographic data and personnel designed to
capture, store, update, manipulate, analyze and display geographically referenced data.
Introduction
● Regarding GIS, most of the questions will be based on maps, photos and diagrams.
● We need to note that the topographic map and orthophoto you receive during the exams are similar
to GIS in that different types of relevant information are put together to make them. Topographic
maps are representations of reality that shows us how things relate to each other in space.
● Maps represent different types of natural and manmade features/information, e.g. roads and
cultivated land in the form of symbols.
● Orthophoto maps are accurate aerial photographs which contain information such as contour lines,
spot heights, names of places etc. They are large scale aerial photographs that show great detail.
● We will not be using computers during examinations so spending a lot of money and time doing
advanced courses in GIS for the purpose of doing well in exams may not be necessary. The excuse
that we can’t do GIS because we don’t have any computers is not relevant.
Satellite Images
● Satellite images are pictures taken from satellites of the Earth.
● This can be done by cameras or other censors that can detect wavelengths outside the visual
spectrum of light.
● We can actually make a picture of something that is not visible to the naked eye.
● The temperature of the sea can been observed.
● The different wavelengths reflected by green and dry vegetation can be captured to see where
drought, disease or development had a detrimental effect on vegetation
The Value of Spatial Images
● Large parts of the Earth can be observed at once (maximum of 1 hemisphere) Satellites images are
taken continuously. Desolated or dangerous areas can be observed safely.
● Changes can be observed over time – there is about 50 years worth of data available.
● Many different applications can make use of satellite images to get information quickly.
● Cheaper than aerial photography in the long run.
● Patterns not visible to the naked eye can be made visible by using other wavelengths than visible
light
, 2
The Five Components Of A GIS:
Hardware, Software, Data, people and organizations, processes. GIS has the same components as other
information systems. It allows us to collect, store and process data to produce maps and answer on spatial
queries. Let us compare GIS with the components of a vehicle
The Body (Hardware) The Fuel (Data/Processing)
Computer hardware Spatial data or geographical data. All data in the GIS
● Central processing unit can be linked to a point, line or area on the ground
● Monitor of which the geographical location is known.
● Keyboard and drivers
● Scanners and digitisers
The Engine (Software/Processing) Driver (People And Organisations/Processing
Computer Programme specially to design to This is the person or actually the team of people
control the input of data into a system where they who link the hardware, software and data together
stored, updated, retrieved and processed to perform various functions. This includes data
collection, analysis, and presentation. and
management.
Concepts Related To GIS:
Remote sensing - getting data about the earth’s surface
from a distance e.g. satellite images
Resolution - The detail and clarity of images in satellite and aerial photographs.
Spatial Resolution - The detail with which a map shows the location and shape of geographic features
Spectral Resolution - Refers to the different kinds of information that can be collected
Database - A storage system with linked tables
Data is facts about reality that has been observed or measured. When data is stringed together it forms
information.
Spatial Data - The location and shapes of geographic features and the relationships between them. E.g.
Coordinates.
& Map Projections
What Is GIS?
● Geographic – place on Earth, Spatial – Where something is on earth?
● Information – data (facts) put together (layering) to make sense e.g. the number of people using a
road. Data used in GIS can be the following: Maps, Remote sensing, Spatial resolution, Spectral
resolution
● System – interrelated information – Using the data to make it mean something.
Definition:
GIS is an organized collection of computer hardware, software, geographic data and personnel designed to
capture, store, update, manipulate, analyze and display geographically referenced data.
Introduction
● Regarding GIS, most of the questions will be based on maps, photos and diagrams.
● We need to note that the topographic map and orthophoto you receive during the exams are similar
to GIS in that different types of relevant information are put together to make them. Topographic
maps are representations of reality that shows us how things relate to each other in space.
● Maps represent different types of natural and manmade features/information, e.g. roads and
cultivated land in the form of symbols.
● Orthophoto maps are accurate aerial photographs which contain information such as contour lines,
spot heights, names of places etc. They are large scale aerial photographs that show great detail.
● We will not be using computers during examinations so spending a lot of money and time doing
advanced courses in GIS for the purpose of doing well in exams may not be necessary. The excuse
that we can’t do GIS because we don’t have any computers is not relevant.
Satellite Images
● Satellite images are pictures taken from satellites of the Earth.
● This can be done by cameras or other censors that can detect wavelengths outside the visual
spectrum of light.
● We can actually make a picture of something that is not visible to the naked eye.
● The temperature of the sea can been observed.
● The different wavelengths reflected by green and dry vegetation can be captured to see where
drought, disease or development had a detrimental effect on vegetation
The Value of Spatial Images
● Large parts of the Earth can be observed at once (maximum of 1 hemisphere) Satellites images are
taken continuously. Desolated or dangerous areas can be observed safely.
● Changes can be observed over time – there is about 50 years worth of data available.
● Many different applications can make use of satellite images to get information quickly.
● Cheaper than aerial photography in the long run.
● Patterns not visible to the naked eye can be made visible by using other wavelengths than visible
light
, 2
The Five Components Of A GIS:
Hardware, Software, Data, people and organizations, processes. GIS has the same components as other
information systems. It allows us to collect, store and process data to produce maps and answer on spatial
queries. Let us compare GIS with the components of a vehicle
The Body (Hardware) The Fuel (Data/Processing)
Computer hardware Spatial data or geographical data. All data in the GIS
● Central processing unit can be linked to a point, line or area on the ground
● Monitor of which the geographical location is known.
● Keyboard and drivers
● Scanners and digitisers
The Engine (Software/Processing) Driver (People And Organisations/Processing
Computer Programme specially to design to This is the person or actually the team of people
control the input of data into a system where they who link the hardware, software and data together
stored, updated, retrieved and processed to perform various functions. This includes data
collection, analysis, and presentation. and
management.
Concepts Related To GIS:
Remote sensing - getting data about the earth’s surface
from a distance e.g. satellite images
Resolution - The detail and clarity of images in satellite and aerial photographs.
Spatial Resolution - The detail with which a map shows the location and shape of geographic features
Spectral Resolution - Refers to the different kinds of information that can be collected
Database - A storage system with linked tables
Data is facts about reality that has been observed or measured. When data is stringed together it forms
information.
Spatial Data - The location and shapes of geographic features and the relationships between them. E.g.
Coordinates.
