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Functions of GIS
30/04/2010
Major Functions of GIS
1. Data Capture
• Data used in GIS often come from many different sources, are of many
types, and are stored in different ways.
• GIS provides tools and a method for the integration of different data
into a format to be compared and analysed.
• Data sources are mainly manual digitization/scanning of aerial
photographs, paper maps, and existing digital datasets. Remote-sensing
satellite imagery and GPS are promising data input sources for GIS.
Major Functions of GIS
2.Database Management and Update
• After data are collected and integrated, the GIS must provide
facilities which can contain and maintain data.
• Effective data management has many definitions but should include
all of the following aspects:
– data security
– data integrity
– data storage
– retrieval, and
– data maintenance abilities.
Major Functions of GIS
3. Geographic Analysis
• Data integration and conversion are only a part of the input phase of
GIS. What is required next is the ability to interpret and to analyse the
collected information quantitatively and qualitatively.
For example, a satellite image can assist an agricultural scientist to
project crop yield per hectare for a particular region. For the same
region, the scientist also has the rainfall data for the past six months
collected through weather station observations. The scientist also has a
map of the soils for the region which shows fertility and suitability for
agriculture. These point data can be interpolated and what you get is a
thematic map showing iso-heights or contour lines of rainfall.
Major Functions of GIS
4.Presenting Results
• One of the most exciting aspects of GIS technology is the variety of
different ways in which the information can be presented once it has been
processed by GIS.
• Traditional methods of tabulating and graphing data can be supplemented
by maps and three dimensional images.
• Visual communication is one of the most fascinating aspects of GIS
technology and is available in a diverse range of output options.
FOUR Ms of GIS
Measurements
Mapping
Monitoring
Modeling
Time-1
Time-2
Time-3
Updating
Adapted from J.Stars and J.Estates
Spatial
Analyses
Measurements
GPS
Data Recording Form
Field Map
Mapping
Deep water table
Shallow water table
Monitoring
July, 1999
June, 2000
Ucchali Lake, Salt Range
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M igran t
Modeling
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M igran t
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M a jo r R iv ers
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Indus Flyway
One way of understanding GIS is to look at
the problems it can solve…
Questions a GIS can answer
• There are five types of question that a sophisticated GIS can
answer
1 Location:What is at...?
– To find what exists at a particular location
– A location can be described in many ways;
• place name,
• post code, or
• geographic reference such as longitude/latitude or x and y
Questions a GIS can answer
2 Condition: Where is it...?
– Find location(s) where certain conditions are satisfied
– e.g., non-forested section of at least 2,000 square metres in
size, within 100 metres of a road, and with soils suitable for
supporting buildings
3 Trends: What has changed since...?
– To find the differences within an area over time
– e.g., changes in land use of a block of land over the last 10 years
Questions a GIS can answer
4 Patterns: What spatial pattern exists...?
– E.g., landslides are mostly occurring where;
• slopes are high,
• soil is not stable and
• vegetation is low
Questions a GIS can answer
5 Modelling: What if...?
– What if a toxic substance seeps into the local groundwater
supply?
– Use GIS to calculate how far it will spread, how quickly, the
level of toxins at a given location, etc.
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