Page123

• Choose an RGB band combination (e.g. 4-5-3) and stretch the image so that you can visually distinguish between different classes.
• Multivariate Analysis >Supervised Classification > Select Training Fields or press on the red TF icon. A new bar will open.
• Press the open icon in TF bar
• Open the file TF_2001_6cl.sav
• Inspect some of the training fields and look at the classes.

To draw some more training fields:

• Digitise an area.
• Finish the polygon with a right click on the mouse.
• In the training fields window name the polygon according to the class and then press enter.
• Save the result (the icon is in the TF bar).

 
 
Running the classification, assigning colours to classes

• Open the un-stretched (original) Landsat 2001 bands number 1, 2, 3, 4, 5, and 7 separately as greyscale images.
• Mark the FCC where you have opened the training fields before.
• Go to Multivariate Analysis >Supervised Classification > Maximum Likelihood.
• Pressing the shift button, mark the un-stretched band number 1, 2, 3, 4, 5, and 7 of Landsat 2001.
• Set the threshold to 0 (zero) so that all pixels get classified
• Press OK
• The process will now run for several seconds to one minute, depending on the image size, the number of bands, and your computer.

Page123