chapter three: components of gis (part 1). a successful gis has 5 critical components: a)hardware...

Chapter Three: Components of GIS (Part 1)

Chapter Three: Components of GIS (Part 1)

5 Critical Components that GIS Can’t Live Without

5 Critical Components that GIS Can’t Live Without

A successful GIS has 5 critical components:

a) Hardware

b) Software

c) Data

d) People

e) Methods

Source:1. http://bgis.sanbi.org/gis-primer/page_12.htm

(a) Hardware & (b) Software(a) Hardware & (b) Software

(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 stand-alone 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) Data Point – Line – Polygon (c) Data Point – Line – Polygon

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

(c) Data: Perhaps the most important component of a GIS. Geographic data and its attributes can be collected in-house, 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

Polygons

Lines

Points

Polygons

Lines

(c) Data Point – Line – Polygon (c) Data Point – Line – Polygon

Source:1. http://newsletter.flatworldknowledge.com/ 2. http://lemonprogis.com/what-are-gis-data-types/

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.

(c) Data Point – Line – Polygon (c) Data Point – Line – Polygon

Source:1. http://www.onemap.sg/

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

Geo-Brain Tickler 4:Geo-Brain Tickler 4:

Scale 1:1000(tourist map)

Scale 1:50,000 (topographic map) Feature Point Line Polygon

Hawker Centre

Heritage Tree

Pedestrian Bridge

Flash Flood

Man Hole

Park Connector

Roundabout

Cemetery

Recycle Bins

Bus Service Route

Choose the most appropriate feature type (point, line or polygon?) for features listed below under the designated scale :

Geo-Brain Tickler 4: The AnswerGeo-Brain Tickler 4: The Answer

Scale 1:1000(tourist map)

Scale 1:50,000 (topographic map) Feature Point Line Polygon

Hawker Centre

Heritage Tree

Pedestrian Bridge

Flash Flood

Man Hole

Park Connector

Roundabout

Cemetery

Recycle Bins

Bus Service Route

Choose the most appropriate feature type (point, line or polygon?) for features listed below under the designated scale :

√√

√

√√

√√

√

√√

Getting to Know GIS Better!Getting to Know GIS Better!

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)

Chapter Three: Components of GIS (Part 2)

(c) Data Vector Format(c) Data Vector Format

Source:1. http://bgis.sanbi.org/gis-primer/page_07.htm2. http://bgis.sanbi.org/gis-primer/page_15.htm3. http://www.geo.hunter.cuny.edu/~rdatta/gis2/lectures/Lecture2/lecture2.htm4. http://usgin.org/content/rasters-and-vectors-comparison 5. http://wiki.gis.com/wiki/index.php/Discrete_and_Continuous_Data

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:

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.

(c) Data Raster Format(c) Data Raster Format

Source:1. http://www.geo.hunter.cuny.edu/~rdatta/gis2/lectures/Lecture2/lecture2.htm2. http://webhelp.esri.com/arcgisdesktop/9.2/index.cfm?TopicName=What_is_raster_data%3F3. http://www.satimagingcorp.com/gallery/ikonos-singapore-lg.html 4. http://usgin.org/content/rasters-and-vectors-comparison5. http://wiki.gis.com/wiki/index.php/Discrete_and_Continuous_Data

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.

Cells / Pixels

Geo-Brain Tickler 5:Geo-Brain Tickler 5:

No. Situation Vector Raster

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.

Choose the most appropriate data format (vector or raster?) for each of the situation encountered below:

Geo-Brain Tickler 5: The AnswerGeo-Brain Tickler 5: The Answer

No. Situation Vector Raster

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.

Choose the most appropriate data format (vector or raster?) for each of the situation encountered below:

√ Temperature is

continuous – no fixed perimeters

√ Playground is discrete in

nature with exact perimeter & distinct location

√ Rainfall is continuous –

its volume gradually increases or decreases

√ Building compound is

discrete in nature – exact perimeter is possible

√

Air quality is continuous – air particles have no

fixed location

√ Earth surface or terrain is

continuous – it either elevates or descends gradually

√ Roads and water bodies

are discrete – exact perimeter is possible

(d) People(d) People

(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.com2. http://flowergarden.noaa.gov3. http://www.gaaged.org

(e) Methods(e) Methods(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.com3. http://www.latitudecartography.co.uk/