When you open SAGA you will see a layout consisting of the following windows:
- Workspace: Is the window where you can, by click through the tabs at the bottom of the window, view processing modules, the data you have loaded and the display maps you have created from your data.
- Work area: Is where image maps and other associated data (Attribute Tables, Histograms, Plots) are displayed.
- Object Properties: This window displays and allows you to alter information about your loaded data and map displays.
- Message Window: Provides information about processes being run by SAGA
Each of the windows can be opened and closed in with the top menu bar icons:
Tools are the SAGA processing functions.
SAGA comes with a comprehensive and growing set of free tools (over 700 in version 2.3). Not all modules are highly sophisticated analysis or modelling tools. Many modules perform simple data operations whilst others other modules represent the state of the art in their field of analysis. They include:
- Data Import & Export
- Cartographic Projections & Georeferencing
- Numerous Raster & Vector Data Tools
- Image Processing
- Terrain Analysis
Tools can also be easily accessed through the top menu ‘Geoprocessing’ drop down menu. I recommend that you use this drop down menu to run SAGA modules as they are grouped into logical processing areas and are thus generally easier to access.
The data the displays any raster (GRID), vector or tables data you have open.
All raster data is displayed as grid layers within a grid system. A grid system groups grid layers that have the same grid cell size, have the same number of rows and columns and they cover the same geographic area. Generally spatial analysis operations are performed on grids with the same grid system
A wide variety of raster data can be imported into SAGA however when raster data is saved from SAGA it is saved in a SAGA format (.sgrd).
It is possible to change the name of loaded grid systems or grid layers in the object properties window.
When vector data is opened into saga is will create a new layer defined as either point, lime or polygon data.
To display the loaded data either right click on a data layer and select show or simply double click on that layer. This data is now opened into a window. To view the data layers displayed in a map window click the map tab.
Multiple data layers from different grid systems can be displayed in a single map layer:
Map layers can be ‘turned off’ by right clicking a map layer and deselecting ‘show layer’ or by simply selecting the layer and pressing ‘enter’. The order in which map layers are displayed can also be changed by right clicking and selecting ‘move up’ or ‘move down’.
Object Properties Tabs
There are a variety of data layer dependent factors that can be edited and viewed that are parameters in the ‘Settings’ area. The ‘Settings’ tab area provides users the opportunity to make adjustments to how a data layer appears in the data and map view windows.
This tab shows information (size, geographic projection) about the selected layer. This data cannot be edited.
Displays the legend or which shows what colours are being used to display which data values from the selected layer.
This window displays the processing history for the selected layer.
It is used with the ‘Action’ ( )tool for displaying the attribute information for a selected grid cell on a grid data layer or the attributes associated with a selected vector feature on a shapes data layer.
Work Area Tools