, GEOGRAPHIC INFORMATION SYSTEMS [GIS]
GIS → computerized system consisting of or hardware, software, data, people &
methods designed to read, manage, manipulate, analyse, model & display spatial
geographic data complex planning & solve management problems
• Geography: Study of the Real World. Physical and cultural world with its spacing
patterns of people, the environment and their interaction with each other.
• Information: Set of processes that use raw data to compile information that can
be used in decision-making processes
• Systems: group of bound objects and activities that act on each other
NOTES: 5 COMPONENTS:
u Store geographic data in u Hardware [CPU, screen, keyboard, mouse
digital format → computer etc.]
u specific data transferred by u Software [ArcView, QGIS, Geomatical]
a user u Data [karate, satellite imagery etc.]
u government, industries, land u People [data capturers etc.]
planners, home affairs, public u Method [GIS Design to USER'S NEEDS]
sector offices, and private
users
u People = key role in the
FUNCTIONS:
development of GIS
software capturing • collecting and capturing data
important geographic • Data storage and management
information • Unlocking and processing data
u Geographers → plan (where • transformation and integration with other
to develop new settlements, data
build dams), where to act • Analysis of data
(pay attention to high levels • representation of data as maps and
of pollutants in a information tables
conservation area) and
evaluate (the effects of
acid mine drainage on local THE VALUE OF DIGITAL DATA
residents)
• ↑ amount of information that can be
u Use → continuously expanded
collected, stored, analysed and displayed
through new data and new
• information = computer system stored and
technology
manipulated in digit form [digit, letter and
u specific and customized data
colour = digit code]
or information
• Information = easily selected, sorted and
graphically displayed
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, 7 ELEMENTS:
1. Sun = source of electromagnetic energy
2. Solar energy = waves > travel through atmosphere [satellites = energy (radio waves)]
3. Energy = Earth's surface > wavebands & interaction with surface [absorbed, radiated,
reflected back]
4. Remote sensors = energy detected in different wavebands &right-isolate information
5. Energy information = electronic signals → ground station (converting information >
maps > satellite imagery)
6. People → satellite imagery = information about Earth
7. Maps / models = develop new knowledge about area / help solve environmental
problems
DATA must first be spatially referenced in a coordinate system = georeference(GeoRef
in short)
SPATIAL & SPECTRAL RESOLUTION
ELECTROMAGNETIC ENERGY SATELLITES & SENSORS
[SPECTRAL RESOLUTION] [SPATIAL RESOLUTION]
→ wavelengths = bands → each = sensors > detect information
→ detect sensors on satellites = energy beyond [describes quantity/size of image elements in
visible spectrum PIXELS]
→ ability of the sensor to detect information
across multiple spectrum bands of the
electromagnetic spectrum
High Resolution Med. Resolution Low Resolution
4 TYPES OF DATA
Spatial features = point, line or area characteristics [ geographic data = shape and the
absolute and relative position of all geographic features displayed]
Non-spatial data ( attribute data ) = information describing the spatial characteristics
of the spatial features or objects
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, RASTER, VECTOR AND REAL WORLD DATA
Vector data = shows geographic
features in the form of basic geometric
objects such as points, lines, and polygons
Raster / GRID data = shows geographic
features by way of arranged patterns
within a grid of square or rectangular
cells. The position of each cell is
determined by the number of its row and
column.
GEOREFERENCED THEMATIC LAYERS:
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