Module 5: Supervised and Unsupervised Image Classification
Supervised classification involves manually choosing representative areas ("signatures") in order to tell the program to classify all areas with similar pixel values to the same class. Unsupervised classification is the opposite, in that the program sorts through and assigns a set number of categories based on pixel values. After this, the categories are grouped manually. For this map of Germantown, Maryland, the categories were determined via supervised classification methods from a image with a band combo of 5, 4, 3 (Red, Green, Blue). This band combo was chosen because it differentiated the vegetation from the urban or fallow areas by including the Near Infrared band (Band 5), which is reflected by healthy vegetation and shows as red areas in the image. Using this image, signature areas were chosen for each of the 8 categories of land use, such as the lake, urban areas, and deciduous forested areas. The image was then classified based on these chosen signatures and the n...