The import function in the free open source SAGA-GIS software makes viewing Landsat data on your own desktop a simple one step process. There is no other tool, free or commercial providing an easier way to import and visualise Landsat data.
The SAGA tool combines three separate functions into one easy dialog box.
- Re-projecting: Landsat data is by default in a UTM North coordinate system which is problematic for southern hemisphere scenes and people who need their data in a geographic (lat/Long) projection. The Landsat import tool allows you to select the scenes UTM hemisphere or geographic coordinate system
- RGB composite display: The import tool allows you directly choose a red, green, blue band combination to display direct on import.
- Contrast enhancing: On import the band combination of choice will automatically appear in the map display window with a histogram stretch applied to produce a scene that is immediately useable. In addition to this SAGA provides a way to enhance the image display on-the-fly based on the current displayed map window allowing the rapid stretching of image data to show the most detail in your area of interest.
The SAGA based Landsat import and display method has some advantages over some web based image viewing services, including:
- Data integration. The use of a desktop GIS platform allows the simple incorporation of other spatial data a user may have. For example GPX and shp files can be simply dragged and dropped into the SAGA display.
- Band combinations: The freedom to choose band combinations is important for users to find the best way to view the landscape feature of interest. For example for fire monitoring and mapping burnt areas the use of a thermal band in a display is very helpful. Thus choosing a 4,5,10 band combination for import produces an instant burnt area visualisarion.
- Internet access limitation: For most people in the developing world and many in the developed world internet connections are slow and unstable. Being able to download once then access, share and explore full resolution imagery is important.
- Multiple image dates: Many Landsat users are interested in using the extensive archive to explore land cover change. With the SAGA import option it is a very simple task to import and display multiple image dates into a single map layer.
- Building analysis skills: Having full resolution multiband Landsat imagery in a desktop image processing package facilitates the ongoing learning about remote sensing and GIS analysis. From understanding basic concepts to building capacity in more sophisticated image analysis such as classification, elevation data integration and modelling.
Two other key features of SAGA-GIS that remove barriers to adoption are its no-installation requirement and GUI. SAGA-GIS is portable software so can be copied to any computer or run straight from USB storage. This fact removes barriers to use by anybody in a large organisation who’s computers are provided without admin privileges and so locked to software installation. The SAGA GUI, whilst not pretty, provides a simple interface similar to many other GIS packages.
You can download SAGA here and import Landsat using the Geoprocessing>Imagery>Landsat Import With Options tool. You will need to:
- Select your downloaded Landsat Geotiff files.
- Select your coordinate system of choice
- Choose and RGB band display option
The Landsat image will automatically open in a display window.