FUNCTIONS
OF GIS:
The Functions of GIS
describe the steps that have to be taken to implement a GIS.
These steps have to be followed in
order to obtain a systematic and efficient system. The steps involved are:
I) Data Capture:
Data
used in GIS often come from many sources. Data sources are mainly obtained from
Manual Digitization and
Scanning of aerial photographs, paper maps, and existing digital data sets.
Remote-sensing satellite imagery and
GPS are promising data input sources for GIS.
In this stage Digitization
(A
conversion process which converts paper maps into numerical digits that can be
stored in the
computer. Digitizing simplifies map data into sets of points,
lines, or cells that can be stored in the GIS computer ) is
carried
out. There are two basic methods of Digitization : Manual Digitizing &
Scanning.
II)
Data Compilation:
Following the digitization of map features, the
user completes the compilation phase by relating all spatial features
to their
respective attributes, and by cleaning up and correcting errors
introduced as a result of the data conversion
process. The end
results of compilation is a set of digital files, each
accurately representing all of the spatial and
attribute data of interest
contained on the original map manuscripts. These
digital files contain geographic
coordinates for spatial objects (points, lines,
polygons, and cells) that
represent mapped features.
III)
Data Storage (GIS Data Models):
Once the data have been digitally
compiled, digital map files in the GIS are stored on magnetic or other digital
media. Data
storage is based on a Generic Data Model that is used to
convert map data into a digital form. The two
most common types
of data models are
Raster and
Vector. Both types are used to simplify the data
shown on a
map into a more basic form that
can be easily and efficiently stored in the
computer.
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Jump to : What is GIS?
Need of GIS? Components
of GIS
