ESA Education Home Earth from Space Environmental Issues Envisat for Schools

Cities
Landscapes
Resources
Multimedia
Image GalleryVideo Gallery
Services
Search in Eduspace

Exercise 2: Land cover classification

Page12

Now that you have become familiar with the Córdoba area, we are going to create a land cover map. This will be done by supervised classification, meaning that the information to map the image for different land cover classes will come from an external source. An algorithm in the software will compare the values in each pixel with the information provided, and will calculate to which class the pixel is most related.

We will do this twice: once for the 2009 image, and then for the 1992 image. In the previous exercise we identified three main land cover classes which will be used in this exercise as well. Such an approach will allow us to quantify each land cover class and assess the surface of the urbanised area, both in 1992 and 2009.

Land cover classification

Open LEOWorks
Open/Multiple Files as Single Dataset: 2009_cordoba_B1 to 2009_cordoba_B7

For LEOWorks3: Open the 2009_cordoba_B1.tif image
In the Image Preview window click OK.
Display band1.

Now repeat the process for the other 2009 bands.

To perform a supervised classification, we need predefined information. This information was provided to you in the form of the files class Urban.shp, Bare soil.shp and Vegetation.shp (LEOWorks4) trainingfields2009 (LEOWorks3) We are first going to investigate these training fields. In order to do this, we need an RGB image.

Display band 4 in red, band 5 in green, and band 3 in blue, in order to create a false colour composite, just like you did in the previous exercise.

Go to Tools - Classification – Supervised - and create 3 classes: Urban, Bare soil, and Vegetation. Import the training fields TF from shapfile (see the LEOWorks Tutorial for more detailed instructions).

For LEOWorks3: Select Multivariate Analysis- Supervised Classification-Select Trainingfields-Open Trainingfields: trainingfields2009.

Page12

The urbanisation of Córdoba
IntroductionBackground
Exercises
Exercise 1: Inspecting the images from 1972 to 2009Exercise 3: Change detection
Eduspace - Software
LEOWorks 3