Remote Sensing - Module 5 - Unsupervised & Supervised Classification

This week's lab module for GIS 5027L Remote Sensing and Photo Interpretation focused on supervised vs unsupervised classification of images in ERDAS Imagine. The module introduced us to several tools such as swipe, flicker, and blend and concepts such as Spectral Euclidean Distance, Neighborhood, and Spectral Confusion. Some of the outcomes from completing this module included manually reclassifying and recoding images to simplify data, creating spectral signatures and AOI features, and recognizing and eliminating spectral confusion between spectral signatures.

The module began with a unsupervised classification exercise of an aerial photograph of the UWF campus. We learned various tools that help complete the process and learned about reclassification and how to merge classes by recoding. This part of the exercise ended with calculating the difference in surface types that occur in the image.

The second part of the module was an exercise in supervised classification which was much more in depth than the unsupervised classification exercise. Supervised classification involves Signature Collection where the user creates class type inputs, which are used to "train" the classifier to recognize features with different spectral characteristics. The user then evaluates the signatures to ensure that they accurately represent unique land covers leading to the most accurate classification. This is done by examining things such as histogram plots and mean plots looking for evidence of spectral confusion and spectral separation. After creating the supervised and distance images it is necessary to compare them to see if you notice any errors. To finish we merged all like classes and added an area column to calculate the area of the final classes.

In the final exercise in the module, we were tasked with creating a supervised classification of Germantown, Maryland.  In this exercise we employed all of the concepts that we learned throughout the lab module to create the final deliverable. According to the governor's office, over the past 30 years, Maryland's population has increased by 30 percent while land consumption has increased by 100 percent. The map below is a current land use map for the area in response to the Maryland governor's desire to work toward Maryland's "Smart, Green, and growing Initiative".