Diploma of Environmental Monitoring & Technology
Study module 1
What is GIS?
MSS025005A
Produce Site Maps
(PSM)
Completion Record
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Type your name here
Available marks
18
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Completion date
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Produce site maps (PSM) - SM 1
What is GIS?
INTRODUCTION
What is GIS?
So who uses GIS?
GIS PROGRAMS
GIS desktop applications
GIS INTERNET APPLICATIONS
Getting a GIS Application for your own computer(s)
GIS DATA
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Vector data
Raster data
ASSESSMENT & SUBMISSION
Knowledge questions
Assessor feedback
Assessment & submission rules
References & resources
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What is GIS?
Introduction
What is GIS?
Just as we use a word processor to write documents and deal with words on a computer, we
can use a GIS application to deal with spatial (Earth based) information on a computer.
The term GIS stands for ’Geographic Information System’. It is a computer program that
displays layers of spatial information in an easy to use and interpret manner.
A GIS application typically consists of the following three components;
Computer Hardware
This is the computers which are used for storing data, displaying graphics and processing
data. There are many types of computer, but most will run GIS applications.
Computer Software
These are the computer programs that run on the computer hardware and allow you to
work with digital data. A software program that forms part of the GIS is called a GIS
application or program.
The most common would be ArcGIS, but there are many other commercial (paid for) and
open source (free) programs available. We will use a program called MapWindow GIS which
is small and free. Software can be PC based (i.e. run from your computer), or it can run from
the internet (such as Google Earth or Maps).
Digital Data
This is the geographical information that you will view and analyse using computer hardware and software. Data will typically consist of map photo layers, which is overlaid with
different types of visual or text based data.
With a GIS application you can open digital maps on your computer, create new spatial
information to add to a map, create printed maps customised to your needs and perform
spatial analysis.
For this course, we will only focus on producing the maps using a GIS program, and will only
glance at the spatial analysis which is a bit more advanced.
So who uses GIS?
GIS is fast becoming the display medium of choice for a lot of information sources. If you can
think of any information that can be displayed on a map, it is best displayed using a GIS
system. For your purposes though, GIS is best viewed as an environmental application, and
is used to display environmental data on maps and aerial photographs.
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Imagine you are working for an environmental consultancy and you make a note of the
water quality characteristics and location of a creek that you sample and perform tests on.
This data could easily be entered into a table such as that seen below;
Site
Latitude
Longitude
Turbidity
G1S1
-32.983409°
151.586506°
37
G1S2
-32.984361°
151.586401°
140
G1S3
-32.986162°
151.585894°
212
G1S4
-32.984854°
151.583668°
45
LT1
-32.984422°
151.586369°
157
LT2
-32.984903°
151.584204°
50
LT3
-32.986916°
151.582980°
412
Table 1.1 – Water quality data from a creek
This information does not look that impressive in a table of data, but we can display it quite
beautifully, and more importantly, productively in a map format. Consider the map below
which shows just the location of the sites.
Figure 1.1 – Water quality sites
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What is GIS?
GIS programs
GIS is a relatively new field and it used to be that computerised GIS was only available to
companies and universities that had expensive computer equipment. These days, anyone
with a personal computer or laptop can use GIS software. Over time GIS Applications have
also become easier to use - it used to require a lot of training to use a GIS Application, but
now it is much easier to get started in GIS even for amateurs and casual users. As we
described above, GIS is more than just software, it refers to all aspects of managing and
using digital geographical data.
GIS desktop applications
You can see an example of what a GIS Application looks like in Figure 1.1 above. GIS
Applications are normally programs with a graphical user interface that can be manipulated
using the mouse and keyboard. The application provides menus near to the top of the
window (File, Edit etc.) which, when clicked using the mouse, show a panel of actions. These
actions provide a way for you to tell the GIS Application what you want to do. For example
you may use the menus to tell the GIS Application to add a new layer to the display output.
Figure 1.2 – MapWindow GIS Application menus and toolbars
Toolbars (rows of small pictures that can be clicked with the mouse) normally sit just below
the menus and provide a quicker way to use frequently needed actions.
A common function of GIS Applications is to display map layers. Map layers are stored as
files on a disk or as records in a database. Normally each map layer will represent something
in the real world such as a roads layer for example will have data about the street network.
When you open a layer in the GIS Application it will appear in the map view. The map view
shows a graphic representing your layer. When you add more than one layer to a map view,
the layers are overlaid on top of each other. The figure below shows a map view that has
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What is GIS?
several layers being added to it. An important function of the map view is to allow you to
zoom in to magnify, zoom out to see a greater area and move around (panning) in the map.
Figure 1.3 - The map view within the MapWindow GIS program showing raster and vector
layers added to it.
Unlike paper maps, the maps displayed in GIS Applications can be changed after they have
been created. You can change the symbology of the map layers to make them appear in
different colours or symbols. Symbology plays an important role in how we interpret maps,
and GIS Applications are very good at letting you change symbology quickly and easily.
Another common feature of GIS Applications is the map legend. The map legend provides a
list of layers that have been loaded in the GIS Application. Unlike a paper map legend, the
map legend or ’layers list’ in the GIS Application provides a way to re-order, hide, show and
group layers.
Changing the layer order is done by clicking on a layer in the legend, holding the mouse
button down and then dragging the layer to a new position. By changing the layer order, the
way that layers are drawn can be adjusted so that what you need to be visible is, and
unwanted layers can be hidden if active (but they can be turned off as well).
Note
The layer order is one of the first things that will cause you grief. You need to remember
that if a layer is active, but not visible, you need to re-order the layer!
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Figure 6: Changing the layer order allows you to adjust the way that layers are drawn.
Generally speaking, a ‘0’ transparency (opaque) layer will hide all other layers if not ordered
correctly.
GIS Internet applications
The internet has proved a significant driver of change in the GIS world. The biggest change
can be found with the amounts of data that can be found for free using internet based
applications such as Google, Yahoo, Bing or OpenStreet Maps.
Although this data is ‘free’, you will not have access to the raw data, just a ‘link’ to it from
the application, but it is still good value!
Getting a GIS Application for your own computer(s)
There are many different GIS Applications available. Some have many sophisticated features
and cost a fortune. In other cases, you can obtain a GIS Application for free. Deciding which
GIS Application to use is a question of how much money you can afford and personal
preference, or it is decided by your workplace.
For these tutorials, we will use the MapWindow GIS Application, which is small and free.
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What is GIS?
GIS Data
Now that we know what a GIS is and what a GIS Application can do, let’s talk about GIS
data. Data is another word for information. The information we use in a GIS normally has a
geographical aspect to it. Think of our example above, about the environmental worker.
They created a table to record water quality data that looked like this:
Site ID
G1S1
G1S2
G1S3
G1S4
LT1
LT2
LT3
Date
12/3/10
12/3/10
12/3/10
12/3/10
12/3/10
12/3/10
12/3/10
pH
6.4
5.6
7.2
7.4
8.6
6.9
7.2
DO (mg/L)
5.6
3.7
4.8
11.5
10.6
8.9
6.4
Cond
(uS/cm)
1143
3245
2756
1894
876
1005
3217
Turb (NTU)
ORP (mV)
23
48
64
120
187
306
413
56
126
203
85
274
244
43
Table 2: Example of data from table 1 with water quality data
The longitude and latitude columns (in Table 1 above) hold geographical data. The Site ID,
date and water quality columns from Table 2 hold non-geographical data. A common
feature of GIS is that they allow you to associate information (non-geographical data) with
places (geographical data).
In fact, the GIS Application can store many pieces of information which are associated with
each place - something that paper maps are not very good at. When the GIS Application
draws the layer, you can tell it to draw the layer based on any of the data attributes
(assuming they display). So, with a GIS Application we have a way to easily change the
appearance of the maps we created based on the non-geographical data associated with
places.
GIS Systems work with many different types of data, but the two critical forms of data that
you need to understand are vector and raster data.
Vector data
The term ‘vector’ has many definitions, but we shall draw upon the basic mathematical
definitions of Cartesian coordinates and geometry, so for us, vector is the term that draws
the three basic geometries of points, lines and polygons (i.e. shapes).
In any GIS application, vector data is stored as a series of X,Y coordinate pairs inside the
computer’s or clouds memory. As we typically use vectors to draw on maps, the cartesin
coordinates are in the form of geographic coordinates so that they display in the correct
location on the map or photo. The figure below shows different types of vector data being
viewed in a GIS application.
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Figure 1.5 Vector data is used to represent points (e.g. sample points or cities), lines (e.g.
rivers and roads) and polygons (e.g. mining or municipal boundaries).
Raster data
For us, a ‘raster’ is an image. The similarity to vector is the use a grid of values, except these
values are not geographic, purely x,y, and they also have a colour associated with them. The
image could be a photo of land taken from a plane or a satellite.
Figure 8: Zoom in to see the individual cells of the data grid that makes up the raster image.
There are many satellites circling the earth and the photographs they take are a kind of
raster data that can be viewed in a GIS. One important difference between raster and vector
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data is that if you zoom in too much on a raster image, it will start to appear ’blocky’. In fact
these blocks are the individual cells of the data grid that makes up the raster image.
Although the data that make up the ‘bitmap’ of the image are not geographic, raster images
can be made geographic by providing the geographic coordinates for a least four points on
the image. This is called geo-referencing, and the subsequent file is called a world file.
Raster images are used to form the ‘backdrop’ to a lot of GIS applications which makes
sense considering that we usually want to display data that relates to real earth.
To summarise, GIS is a visual way to display geographical and non-geographical data in a
visual format that allows users to understand geographic related information easily. The
image below shows an example of the use of GIS with the Westlakes water quality
monitoring program and other information. Your assessment will be based on producing a
series of maps in a GIS program similar to the one displayed below.
Figure 1.6 – Example of GIS data displayed in a GIS application (Google Earth)
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Assessment & Submission
This section provides formative assessment of the theory. Answer all questions by typing
the answer in the boxes provided. Speak to your teacher if you are having technical
problems with this document.
Knowledge questions
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Type brief answers to each of the questions posed below.
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All answers should come from the theory found in this document only unless the
question specifies other.
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Marks shown next to the question should act as a guide as to the relative length or
complexity of your answer.
1. What does the term ‘GIS’ stand for? 1mk
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2. What is meant by the term ‘spatial’ data? 1mk
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3. What three key components make up a GIS system? 3mk
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4. Who uses GIS? What can GIS be used for? 2mk
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5. Describe the key differences between desktop and internet based applications. 4mk
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Click here to enter text.
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6. What is the difference between geographic and non-geographic data? Provide an
example of each type. 4mk
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7. In GIS, what is meant by the term ‘vector’? 1mk
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8. In GIS, what is meant by the term ‘raster’? 1mk
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9. What happens when you zoom into a raster image? 1mk
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Assessor feedback
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Assessment & submission rules
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Attempt all questions and tasks
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Write answers in the text-fields provided
Submission
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Use the documents ‘Save As…’ function to save the document to your computer using
the file name format of;
Yourname-PSM-SM-1
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email the document back to your teacher
Penalties
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If this assessment task is received greater than seven (7) days after the due date, it may
not be considered for marking without justification.
Results
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Your submitted work will be returned to you within 3 weeks of submission by email fully
graded with feedback.
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You have the right to appeal your results within 3 weeks of receipt of the marked work.
Problems
If you are having study related or technical problems with this document, make sure you
contact your assessor at the earliest convenience to get the problem resolved. The contact
details can be found at;
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www.cffet.net/env/contacts
References & resources
Resources
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http://www.mapwindow.org/
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http://www.qgis.org/en/site/
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https://esriaustralia.com.au/about-gis
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https://learn.arcgis.com/
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www.gislounge.com/learn-gis-for-free/
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www.esri.com/training/main
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References
Note that some of these resources might be available from your teacher or library
Brimicombe, A. (2010). GIS, Environmental Modelling & Engineering. 2nd Ed. Boca Raton:
CRC press.
Burden, F. E. (2002). Environmental Monitoring Handbook. McGraw-Hill Professional.
DIPNR. (2004). Guideline for the preapration of Environmental Management Plans. Sydney:
DIPNR.
Ferrier, R. C. (2010). Handbook of Catchment Management. Oxford: Wiley-Blackwell.
Newton, A. (2007). Forest Ecology and Conservation. Oxford: Oxford University Press.
Schneider, R. R. (2011). MapWindow: Quick Start Tutorial. MapWindow 4.8.6. Edmonton:
Free Software Foundation.
Sutherland, W. (2006). Ecological Census Techniques. 2nd Ed. Cambridge: Cambridge
University Press.
Sutton, T. E. (2009). A Gentle Introduction to GIS. Eastern Cape, South Africa: Chief
Directorate: Spatial Planning & Information, Department of Land Affairs, Eastern
Cape.
Acknowledgement
This Study module was unashamedly derived in whole with minor adjustment from the
open source work of Sutton Et al.
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