Obtaining the width and height of a raster

All raster layers have a width and height in pixels. Because remote sensing data can be considered an image as well as an array or matrix, you will often see different terms used, including columns and rows or pixels and lines. These different terms surface many times within the QGIS API.

Getting ready

We will use the SatImage raster again, which is available at https://geospatialpython.googlecode.com/files/SatImage.zip.

Place this raster in your /qgis_data/rasters directory.

How to do it...

1. Start QGIS.
2. From the Plugins menu, select Python Console.
3. In the Python Console, load the layer and ensure that it is valid:

   rasterLyr = QgsRasterLayer("/qgis_data/rasters/satimage.tif", "satimage")
   rasterLyr.isValid()
   

   Check the name of SatImage after unzipping.

4. Obtain the layer's width, which should be 2592:

   rasterLyr.width()
   

5. Now, get the raster's height, which will return 2693:

   rasterLyr.height()
   

How it works...

The width and height of a...