1. Session 3: Manipulating map views Mapping files with
coordinates Concepts: Geodesy and Map Projections
2. REVIEW: Change shapefile display
3. 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
4. 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
5. You should now see an outline where the fill was before
6. Boundaries for each layer are slightly different Each layers
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
7. OR reduce layers to really take in boundary (frontera)
differences try turning off layer 3 -- the one with most
detail
8. Importing data based on coordinates from a pre-existing
table or spreadsheet
9. To do this, you first open libre office and open the
coordinate file
10. 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
11. Click Save as under the File drop-down menu
12. Choose Text CSV (.csv) from the Save as type drop- down
menu
13. Once loaded into QGIS, you will be asked to input the field
delimiter that you first used when creating your database. So its
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
14. To load the database, in the top window look for layer,
then click on add delimited text layer
15. 1. We need to define our file. To do this click on Browse
2. Find and highlight your file and click OK
16. try turning off layer 3 the one with most detail we have
converted our files to be comma delimited files
17. Now we need to define our delimiter. For our purposes,
check the Comma checkbox.
18. 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
19. Now we are going to do some checks to see if our data is in
the right place
20. You can click on a gps coordinate point and check that the
location identified in the attribute table seems to correspond with
it
21. Go to ABC icon and click to see what labels tell us Does
the city correspond with the hospital?
22. 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
23. Is this tete?
24. OK! Now you try using your own data
25. 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
26. Earth to Globe to Map = Source:
http://www.esi.utexas.edu/gk12/workshops/gis/ppts.php
27. All projections have distortions Shape Area Distance
Direction Angle Source:
http://www.esi.utexas.edu/gk12/workshops/gis/ppts.php
28. 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 Source:
http://www.esi.utexas.edu/gk12/workshops/gis/ppts.php
29. 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 Source:
http://www.esi.utexas.edu/gk12/workshops/gis/ppts.php
30. 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 Source:
http://www.esi.utexas.edu/gk12/workshops/gis/ppts.php
