Remote Sensing Lab 8: Spectral Signature Analysis

Goal

In the final lab of Remote Sensing of the Environment we will be gaining experience on interpretation and measurement of spectral reflectance of different materials on the Earth's surface. We will learn how to how to collect spectral signatures from remotely sensed images. We will also graph them, as well as perform analysis on them and verify if they will pass spectral separability tests.

Methods

For this lab we are going to be sampling the wavelengths from 12 different locations, ground surfaces, across the Eau Claire area. These 12 surfaces are
1-Standing Water
2-Moving Water
3-Vegetation
4-Riparian Vegetation
5-Crops
6-Urban Grass
7-Dry Soil (uncultivated)
8-Moist Soil (uncultivated)
9-Rock
10-Asphalt Highway
11-Airport Runway
12-Concrete Surface (parking lot)

Using the same image we had to take a sample of each area, starting with Lake Wissota. We used the drawing tool to capture a section of Lake Wissota, and then used the supervised tool, signature editor, all found under the Raster Tab. This tool would bring up an empty box where we can import our Lake Wissota polygon. After bringing in the area we looked at the spectral graph, below.

Here we can see what the spectral signature is for the standing water of Lake Wissota. Looking at the Graph we can see that Band Layer 1 is the highest, while Band Layer 4 and 6 are the lowest. We then did the same process for the next 11 ground surfaces. After capturing all 11 surfaces they are imported into the same signature editor and compared to each other using their spectral signatures. All 12 could be put onto one graph, below.

After bring in all 12 surface features we could tell what a good Band Layer would be to use if you did not know what was at the ground level. For this lab I found that Band Layer 5 would be the best layer to use since it had the greatest differences, and Band Layer 2,3,4 would be the worst ones to use since they are so close to each other.


Results

In Lab 8 we found that everything has a different spectral signature, and if you know the spectral signature we can then find out what it is that we are looking at. We found that Band Layers 5 and 6 would be the best to use and Bands 2,3, and 4 would be the worst, band 1, although not ideal, could be a decent one to use.

Resources
Image Provided by Dr. Wilson (University of Wisconsin-Eau Claire-Geography and Anthropology Department)