Marine Data Literacy 2.0

Providing instruction for managing, converting, analyzing and displaying oceanographic station data, marine meteorological data, GIS-compatible marine and coastal data or model simulations, and mapped remote sensing imagery

 

 

 

 

Home > 2. Marine GIS > 2.3 Project Map

2.3 Creating a Project Map in Saga

  • Exercise Title:  Creating a Project Map in Saga

  • Abstract:  A global shapefile of country boundaries is loaded into Saga and displayed, demonstrating the most basic way to create a map.  The area of the map is zoomed to approximate the project area dimensions, and the zoomed map is saved as a "project" in Saga, using a special auxiliary format.

  • Preliminary Reading (in OceanTeacher, unless otherwise indicated):

  • Required Software:

    • Saga (version 2.1.2 or higher)

  • Other Resources: 

  • Author:  Murray Brown

  • Version:  1-26-2015

1.  Download the world borders zipfile, and save it to the folder DATA > BASEMAP > BORDERS.  Then unzip it in place.
2.  Run Saga.  Then select FILE > SHAPES > LOAD SHAPES, and navigate to the world borders dataset and open it.
3.  The loaded data object, will appear in the workspace, in the data tree.  Notice that it is classified as a polygon shape.

Right-click on the object, and select ADD TO MAP.

4.  This map appears.  You can size it however you want, by dragging a corner outward or inward.
5.  Shapefiles always include at least 3 files:
  • *.shp
  • *.shx
  • *.dbf

The attribute table (the *.dbf file) can be examined to see what information is available about the physical features that have been drawn.

To see the table, right-click on the data object, and select ATTRIBUTES > SHOW TABLE

6.  Now you can see the contents of the attributes table.  These columns have cryptic labels, but a little research can yield these explanations:
  • FIPS - A US government code system for country names
  • ISO2 and ISO3 - The International Organization for Standards 2- and 3-letter code systems to identify countries
  • UN - The United Nations codes for the countries
  • Region and Subregion - Subdivisions from the UN system
  • Lat and Lon - Geographic coordinates of the country's centroid (for labeling purposes)

To find Liberia (which isn't easy to find in this long table), right click on the label row, and select SORT FIELDS.

7.  When this window appears, select SORT FIRST BY UN, and leave the second and third choices empty.  Then click OK.
8.  Now you can easily find Liberia alphabetically.
9.  If you look very carefully, you can see that the record selected in the table is shown as red/yellow in the map, to help you locate it.

You can close the attributes table now.

10.  In the properties window, select OPTIONS > COLORS > TYPE > GRADUATED COLOR
11.  In the properties window, also select ATTRIBUTE-UN to specify that the coloring will be according to the UN code numbers.
12.  Click COLORS, and a small control showing THREE DOTS (called an ellipsis) appears.  Click the ellipsis.
13.  To select a larger number of colors, click on COUNT, and set it to 50.  Then click OK.

NOTE:  50 is arbitrary.  Try values from 5 to 150 to see what effect it has.

14.  To use a colorful palette, click on PRESETS, and select RAINBOW.  Then click OK.

Click OK again to close the COLORS window.

NOTE:  The RANDOM color set would also be a good choice, because the numerical values of the attribute UN aren't scientifically important.

15.  Now to make these changes effective, you must click SETTINGS-APPLY at the bottom of the panel.
16.  Now you can see each country with a separate color.
17.  Find the ZOOM tool along the top border of Saga, and drag it to select approximately this area of western Africa.

You can always reverse a zoom action, but clicking on ZOOM TO PREVIOUS EXTENT.

18.  Now this is approximately what the entire Saga screen looks like.  Liberia is the bright gold country.
19.  At the bottom of the properties window, find and click on the ATTRIBUTES tab.  Then along the top of the Saga window, find and click on the ACTION tool (an arrow).
20.  Click on Liberia to see its attribute information displayed in the properties window.

[You may have to click a different country first, as Liberia has already been selected from the attributes table, which much be unlocked before the attributes appear.]

 

21.  This completes a short demonstration of some common operations with shapes.  You can further explore what Saga can do on your own. 
22.  Now we need to begin finalizing and saving our project map.  First, at the top of the properties window change the name to World Borders.  Then at the bottom click SETTINGS > APPLY
23.  This changes the display name in the workspace.
24.  Now, we need to save this map, so we can re-draw it quickly.  Select FILE > PROJECT > SAVE PROJECT AS, then navigate to PRODUCTS > SAGA > PROJECTS and enter the name map_liberia.sprj (stands for Saga PRoJect).
25.  You can close Saga now.  To return to this map, simply run Saga, and select FILE > PROJECT > LOAD PROJECT and navigate to the PROJECTS folder to open map_liberia.sprj
26.  OPTION.  If you will be working in Google Earth (GE) for mapping, then in Saga you can select TOOLS > IMPORT/EXPORT > GDAL/OGR > EXPORT SHAPES TO KML.
  • For SHAPES, select the World Borders you must mapped above.
  • To select the target file location and name, click on the ellipsis (...).

27.  Navigate to PROJECTS > LIBERIA > PRODUCTS > SAGA > VECTORS and enter the filename world_borders_0p3.kml.  Then click OK.

NOTE:  "0p3" means 0.3.

28.  If GE is installed, then you can simply double click on the new KML file to see the new map.  Here's the central Liberia coast.  The new KML vectors are in red.
29.  Here's the original GE coastline, with the new file.  You can see the older one is not as detailed as the new one.
30.  Throughout all of MDL, if you are interested in GE visualizations, then simply use the above few steps to make a separate set of KML vectors, parallel to the shapefile vectors we usually make here.