AFRICAN
CONSERVATION AND WEB SITES FOR AFRICA FROM
AFRICANWEBSITES.NET
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GIS – a world of spatial information
| | GIS Introduction
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Remote Sensing
Introduction
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| | Data Sources | |
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GIS & Remote Sensing Resources
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GIS stands for Geographical Information Systems, a computer based system for the management and analysis of spatially referenced data. Basically, a GIS can have four main functions:
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 "GIS uses information that is stored on databases and places it on a map, making it clear to read and understand." |
| Database
and mapping
system A GIS is a spatial database and mapping system in one: a powerful set of tools to handle and access large amounts of data with both a spatial and a thematic (attribute) component:
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Analytical
functions
A GIS helps to discover
the meaning in spatial relationships and among events in time. One important
feature of a GIS is that you can geographically display objects according
to the attributes in your database. Another important feature is the possibility
to query, overlay and analyse your data. These analytical functions provide
means for deriving new information from existing data.
GIS provides the user the
ability to analyze spatial data in a visual format. The analytical ability
of GIS has typically been used in fields such as forestry, agriculture, natural
resource management, environmental planning and conservation.
Data
structure
There are two basic formats
for spatial data storage:
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Raster data - continuous spatial data, represented by grid cells of a certain size (resolution). Grid cells are mostly rectangular, but other shapes, like triangular, are also used.
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Vector data (object oriented) - discrete, bounded objects, represented as points, lines or areas (polygons). In case of a 3D GIS this can also be volumes.
Typically, spatial data in a GIS is stored in different layers, like landform, landcover, soil, drainage, settlements, vegetation, etc. Together the different layers form a representation of the real world. This layering is a major difference with paper maps, as users can selectively display information according to their needs. Furthermore, the layering makes it possible to perform complex relational analysis.
What do you need to use a GIS?
Building up and maintaining
a geographical information system requires:
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Hardware (computers and peripherals)
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GIS, image processing or integrated software
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Data
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(Skilled) People
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Methods and procedures for spatial analysis and interpretation
Data for GIS applications
Data for GIS applications includes:
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Digitised and scanned data
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GPS field sampling data
- (Georeferenced) databases
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Remote sensing and aerial photography
The quality
of a GIS depends on the quality of the input:
Better data leads to better information, and better information leads
to better decisions.
Important input sources for a GIS are Remote
Sensing, cartography (including digitizing) and photogrammetry.
Use the index to read more about spatial information technology. The GIS
& Remote Sensing Resources section will guide you to extensive
information on the internet, including online tutorials, directories and
data resources.
| | GIS Introduction
| | Remote
Sensing Introduction |
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| | Data
Sources
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| | GIS & Remote Sensing Resources
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If
you would like to contact us about GIS and Remote Sensing please email
arend@africanconservation.org
