GIS 4035: Module 7 - Image Preprocessing 2: Spectral Enhancement and Band Indices

This week continued the work with Erdas Imagine and satellite imagery, beginning a deeper delve. Imagery from Landsat 5 Thematic Mapper was provided with the six bands that maintain the same spatial resolution included (Blue, Green, Red, Near Infaread and two mid-level Infrared bands). Several exercises provided practice manipulating and interrogating the images, combining various bands so as to make various features stand out. For example, the most common false color combination where the display layers for Red, Green and Blue are re-mapped respectively to Near IR, Red and Green was given a good workout.

The deliverables this week were created as part of a treasure hunt. The features were described spectrally and had to be located somewhere in the study area of the imagery. Feature 1 represented typical water features, which tend to absorb most electromagnetic radiation in the near infrared band. Feature 2 turned out to be snow, ice and glaciers, which appear bright (high radiometric values) in bands 1-4, but quite dark in bands 5 and 6. Feature 3 was an unusual water feature that had radiometric gradations in 1 - 4 and was somewhat brighter than other water features in these bands. Each feature was displayed in a map with a different combination of bands being used along the RGB display bands.

Feature 1: A Lake

Feature 2: Ice & Snow

Feature 3: Another Lake, with radiometric gradations