Chapter Three:
Components of GIS (Part 1)
A successful GIS has 5 critical components:
Source:
1. http://bgis.sanbi.org/gis-primer/page_12.htm
a)
Hardware
b)
Software
c)
Data
d)
People
e)
Methods
(a)
Hardware:
Hardware is the computer system on which a GIS operates. Today, GIS runs on a wide range of
hardware types, from centralized computer servers to laptops and smart phones used in standalone or networked configurations.
(b) Software:
GIS software provides the functions and tools needed to store, analyze, and display geographic
information.
Source:
1. http://www.iceburghsolutions.com/services/services.htm
2. http://bgis.sanbi.org/gis-primer/page_12.htm
(c)
Points
Polygons
Data:
Perhaps the most important component of a GIS.
Geographic data and its attributes can be collected inhouse, sourced or purchased from data providers.
All geographic features on the earth can be
characterized and represented as one of three basic
feature types  points, lines, and polygons:
Points
Lines
Lines
Polygons
Source:
1.
http://www.gisdevelopment.net/technology/gis/techgi0047a.htm
2.
http://bgis.sanbi.org/gis-primer/page_12.htm
3.
http://en.wikipedia.org/wiki/GIS_file_formats
i.
Points are used to represent single location
feature like a tree, a fire pump, a lamp post, a
bus stop, a taxi stand, a monument…etc. A
point can also be displayed as a symbol.
ii. Lines are used to represent linear features like
rivers, roads, canals, drainages, water pipes,
gas pipes, networks…etc.
iii. Polygons are used to represent enclosures or
areas like lakes, boundaries, building
footprints, flooded areas, contaminated areas,
reservoirs, forested areas, nature
reserves…etc.
Source:
1.
http://newsletter.flatworldknowledge.com/
2.
http://lemonprogis.com/what-are-gis-data-types/
Please do note that under different map
scale, feature type of certain features may
change to represent the real world better.
Aljunied MRT station is displayed as
a polygon in scale 1:1000
Aljunied MRT station is displayed as
a point (represented by a MRT
symbol) in scale 1:20,000
Source:
1.
http://www.onemap.sg/
Choose the most appropriate feature type (point, line or polygon?) for features listed below under the
designated scale :
Scale 1:1000
(tourist map)
Scale 1:50,000
(topographic map)
Feature
Hawker Centre
Heritage Tree
Pedestrian Bridge
Flash Flood
Man Hole
Park Connector
Roundabout
Cemetery
Recycle Bins
Bus Service Route
Point
Line
Polygon
Choose the most appropriate feature type (point, line or polygon?) for features listed below under the
designated scale :
Scale 1:1000
(tourist map)
Scale 1:50,000
(topographic map)
Feature
Point
Line
√
Hawker Centre
Heritage Tree
Polygon
√
Pedestrian Bridge
√
Flash Flood
√
Man Hole
√
√
Park Connector
Roundabout
√
Cemetery
√
Recycle Bins
Bus Service Route
√
√
Did you get all the answers correct…?
No worries! As you explore more about GIS in this e-Learning section,
you definitely understand more. 
Let’s move on to the next chapter to continue our learning journey…
Chapter Three:
Components of GIS (Part 2)
Let’s continue with the third component of GIS  Data:
Each feature type can be displayed in both two types
of data formats/structures  Vector & Raster:
Source:
1.
http://bgis.sanbi.org/gis-primer/page_07.htm
2.
http://bgis.sanbi.org/gis-primer/page_15.htm
3.
http://www.geo.hunter.cuny.edu/~rdatta/gis2/lectures/Lecture2/lecture2.htm
4.
http://usgin.org/content/rasters-and-vectors-comparison
5.
http://wiki.gis.com/wiki/index.php/Discrete_and_Continuous_Data
1) In vector format:
 Each feature is composed by a vertex or vertices.
Each vertex consists of a pair of X and Y
coordinate.
 Point features are defined by one coordinate pair –
a vertex.
 Line features are defined by a string of vertices –
also known as an “arc”.
 Polygonal features are defined by a set of closed
coordinate pairs.
 Vectors are best suited to represent features that
have distinct boundaries or limits that are discrete
in space and time, e.g. buildings, parks or roads.
 Discrete data is helpful in showing exact location,
perimeter, and length of objects.
2) In raster format :
 A raster consists of a matrix of cells (or pixels) organized into rows and
columns (or a grid). Each cell contains a value representing information of the
feature being represented.
 Rasters represent points by a single cell, lines by sequences of neighbouring
cells and polygons/areas by collections of contiguous cells.
 Rasters are best suited to representing continuous data  geographic
phenomena that do not have well-defined boundaries and are found
everywhere throughout the mapped area.
 Continuous data are often shown in a colour scale in order to show change
over an extent, e.g. temperature across a region.
Source:
1.
http://www.geo.hunter.cuny.edu/~rdatta/gis2/lectures/Lecture2/lecture2.htm
2.
http://webhelp.esri.com/arcgisdesktop/9.2/index.cfm?TopicName=What_is_raster_data%3F
3.
http://www.satimagingcorp.com/gallery/ikonos-singapore-lg.html
4.
http://usgin.org/content/rasters-and-vectors-comparison
5.
http://wiki.gis.com/wiki/index.php/Discrete_and_Continuous_Data
Cells / Pixels
Choose the most appropriate data format (vector or raster?) for each of the situation encountered below:
No.
Situation
1
I want to map out the sea temperature of South China Sea during
the Monsoon season between 2000 and 2010.
2
I want to display the location of all children playgrounds within
HDB estates in Ang Mo Kio.
3
I want to produce a map that shows the average daily rainfall
volume in Bukit Batok area for the first-half of the year.
4
I need a map that displays the exact compound of my school.
5
I have to represent the overall air quality of Singapore for the
past five years on a map.
6
I need to produce a map that showcases the hilly area of
Sumatra.
7
I need to map out all major roads, rivers and canals in Singapore.
Vector
Raster
Choose the most appropriate data format (vector or raster?) for each of the situation encountered below:
No.
Situation
1
I want to map out the sea temperature of South China Sea during
the Monsoon season between 2000 and 2010.
2
I want to display the location of all children playgrounds within
HDB estates in Ang Mo Kio.
3
I want to produce a map that shows the average daily rainfall
volume in Bukit Batok area for the first-half of the year.
4
I need a map that displays the exact compound of my school.
5
I have to represent the overall air quality of Singapore for the
past five years on a map.
6
I need to produce a map that showcases the hilly area of
Sumatra.
7
Vector
Temperature is
continuous – no fixed
perimeters
√
Rainfall is continuous
– its volume gradually
increases or decreases
√
Air quality is continuous
– air particles have no
fixed location
Earth surface or terrain is
continuous – it either elevates
or descends gradually
I need to map out all major roads, rivers and canals in Singapore.
√
Raster
√
Playground is discrete in
nature with exact perimeter
& distinct location
√
Building compound is
discrete in nature – exact
perimeter is possible
√
√
Roads and water bodies
are discrete – exact
perimeter is possible
(d) People:
GIS is pointless without the people who manage,
analyse and map out geospatial data to resolve real
world problems.
People who are specialized in GIS can be
designated as GIS specialist, geospatial consultant,
GIS manager and others, though not really common
in Singapore.
Source:
1.
http://www.cadalyst.com
2.
http://flowergarden.noaa.gov
3.
http://www.gaaged.org
(e)
Methods:
A successful GIS operates according
to a well-designed implementation
plan and procedures, which are the
models and operating practices
unique to each organization.
Source:
1.
http://bgis.sanbi.org/gis-primer/page_12.htm
2.
http://www.esri.com
3.
http://www.latitudecartography.co.uk/