“Raster data consists of a matrix of cells where each cell represents a specific value on the earth surface. QGIS can read and write different types of raster formats.”
QGIS used the library called GDAL to read and write various formats. Rasters are commonly used for making base maps ie XYZ tiles in QGIS all render raster data. In this module, we will explore the various methods available for loading raster data.
Goal: To explore how to load raster data in QGIS
Note the extensions of all the layers in the folder.
Why did you select the extension .tif?
Raster data is cell-based and this data category also includes aerial and satellite imagery. Raster data is grouped into two categories continuous and discrete. Example of discrete raster data is population density whilst continuous data examples are temperature and elevation. Whilst loading data it QGIS it is important to filter the data based on the extensions. The most common format of raster data is geotiff that can have an extension .tif/.TIFF/.tiff. Loading layers using the browser panel has significant advantages because it automatically filters for the correct format to be loaded in QGIS. A raster layer can also have supporting files which we saw in the exercise folder. A typical layer can have the following files associated with it.
||A file with projection definition for the layer|
||QGIS specific file that has information about how the raster should look like. (Symbology)|
||A file with raster statistics|
||Metadata file describing the characteristics of the raster|
Click here to download the sample data for the lesson.