QGIS Module 3

Session 3:
•Manipulating map views
•Mapping files with coordinates
•Concepts: Geodesy and Map Projections

REVIEW:
Change shapefile display

Right click on the
layer and select
“Properties”
Note: In order to see other
layers that we will add later,
we need to remove the Fill
on our newly opened layer

1. Once in Layer properties,
make sure you are under the
“Style” tab. Then, click on
the “Change” button2. In the Symbol Properties
menu, select “Outline:
Simple line” from the drop-
down menu

You should now see an
outline where the fill was
before

Boundaries for each layer are
slightly different
Each layer’s boundary line should be thinner
and the color lighter as the layers decrease in
size. In this case:
• .88 for province layer
• .44 for district layer
• .24 for any smaller area layers
• And the line colors should be slightly lighter
as the layers decrease in size, but of the
same general color scheme

OR reduce layers to really
take in boundary (frontera)
differences
try turning off layer 3 -- the
one with most detail

Importing data based on
coordinates from a
pre-existing table or
spreadsheet

To do this, you first open libre
office and open the coordinate
file

We can create a new vector
layer in QGIS from a
spreadsheet or database
that contains GPS
coordinates. First we need to save our
database in a format that QGIS
can read. To begin, make sure
your database or spreadsheet is
open in LibreOffice

Click “Save as…” under the
File drop-down menu

Choose “Text CSV (.csv)”
from the Save as type drop-
down menu

Once loaded into QGIS, you will be asked to
input the field delimiter that you first used
when creating your database. So it’s
important to note what was chosen before
moving further!
QGIS accepts Tab, Space,
Comma, Semicolon and colon.
However, for our purposes,
choose comma from the “Field
Delimiter” drop down menu. Then,
Click OK

To load the
database,
in the top
window
look for
layer, then
click on
“add
delimited
text layer”

1. We need to define our file. To
do this click on “Browse”
2. Find and highlight your file
and click “OK”

try turning off layer 3 the one with most
detail
we have converted our
files to be comma
delimited files

Now we need to define our
delimiter. For our
purposes, check the
“Comma” checkbox.

Next, we will need to define
our coordinates. QGIS does a
pretty good job of doing this
for you, but double check
using the preview provided
in the “Sample Text”
window.
If the table in the
“Sample Text”
window matches
your database or
spreadsheet. Click
“OK”

Now we are going to do some
checks to see if our data is in
the right place

You can click on a gps
coordinate point and check
that the location identified
in the attribute table seems
to correspond with it

Go to ABC icon and click
to see what labels tell us
Does the city correspond
with the hospital?

To check our locations we can
also open our attribute data
and zoom in on location
• Highlight the whole row
• Use the zoom then minimize
and switch to your map

OK! Now you try using your
own data

Geodesy and Map Projections
• Geodesy - the shape of the earth and
definition of earth datums
• Map Projection - the transformation of a
curved earth to a flat map
Source: http://www.esi.utexas.edu/gk12/workshops/gis/ppts.php

Earth to Globe to Map
=

All projections have distortions
• Shape
• Area
• Distance
• Direction
• Angle

Summary Concepts
• To prepare a map, the earth is first reduced
to a globe and then projected onto a flat
surface
• Three basic types of map projections: conic,
cylindrical and azimuthal
• A particular projection is defined by a datum,
a projection type and a set of projection
parameters

Projections Preserve Some
Earth Properties
• Area - correct earth surface area (Albers Equal Area)
important for mass balances
• Shape - local angles are shown correctly (Lambert
Conformal Conic)
• Direction - all directions are shown correctly relative to
the center (Lambert Azimuthal Equal Area)
• Distance - preserved along particular lines
• Some projections preserve two properties

Types of Projections
• Conic (Albers Equal Area, Lambert
Conformal Conic) - good for East-West land
areas
• Cylindrical (Transverse Mercator) - good for
North-South land areas
• Azimuthal (Lambert Azimuthal Equal Area) -
good for global views

Conic Projections
(Albers, Lambert)

Cylindrical Projections
(Mercator)
Transverse
Oblique

Azimuthal
(Lambert)

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