This tutorial explores some basic raster operations in QGIS such as viewing, mosaicing and subsetting.
We will download some public domain raster data for Brazil and view it in QGIS. Next, we will merge these into a single mosaic and clip it using a country boundary to get a single seamless dataset for the country.
We need Brazil country boundary to clip our raster. You can get the Admin 0 - Countries shapefile from Natural Earth.
NASA/GSFC, Rapid Response site has a good collection of near real-time satellite imagery. A good regional product is USDA Foreign Agricultural Service (FAS) subsets.. We will use 2km resolution FAS subsets for Brazil for this tutorial.
Here is how to search and download the revelant data.
Repeat the process for all 7 FAS subsets for Brazil.
For convenience, you can directly download sample data used in this tutorial from links below.
ne_10m_admin_0_countries.zip FAS_Brazil1.2013363.aqua.ndvi.2km.tif FAS_Brazil2.2013363.terra.ndvi.2km.tif FAS_Brazil3.2013363.aqua.ndvi.2km.tif FAS_Brazil4.2013363.aqua.ndvi.2km.tif FAS_Brazil5.2013363.aqua.ndvi.2km.tif FAS_Brazil6.2013363.terra.ndvi.2km.tif FAS_Brazil7.2013363.aqua.ndvi.2km.tif
The Raster menu in QGIS comes from a core plugin called GdalTools. If you do not see the Raster menu, enable the GdalTools plugin from Plugins ‣ Manage and install plugins ‣ Installed. See Using Plugins for more details.