The point of this lab was mainly to learn skills in measurement and interpretation of spectral signatures. Spectral signatures are essentially the unique levels of reflectance at various wavelengths. Understanding spectral signatures can help you with identification of features, as well as with studying the health and quality of certain features from aerial and satellite photographs. The main goals of this lab was to
1. Understand how to collect spectral signatures
2. Understand how to analyze spectral signatures
Methods and procedures
To collect spectral signatures
1. The first step in this lab was to import the image eau_claire_2000.img into the viewer.
2 Connect the viewer to Google earth in order to more easily identify various features.
3. Zoom in to an area and draw a polygon, then click on raster, supervised, and spectral editor to bring up the spectral signature for the area inside of the polygon.
4. Repeat the process, drawing polygons in different features, and adding these spectral signatures to the same signature editor.
To analyze spectral signatures
1. Highlight all signatures in the signature editor window.
2. Compare the spectral signatures in the Signature Mean Plot Window
3. Switch between single and multiple mode in order to view the spectral signatures individually and within the context of other spectral signatures.
In terms of analyzing, there may be some questions that you will need to look up using outside information. For instance when trying to understand why vegetation has a certain spectral signature, it may be useful to look up information about cell walls and chlorophyll and understand what wavelengths of electromagnetic radiation they absorb and reflect.
Results and Conclusions
The resulting spectral signatures that I collected in this lab can be seen in the picture below.
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| Spectral signatures for various features in the Eau Claire area |
This lab was beneficial in learning how to collect and analyze spectral signatures. There is obviously more that can be done with spectral signatures, but I think it was good that we know have a basic understanding of what they are and how to collect them.
Source
Satellite Image: eau_claire_2000.img, Earth Resources Observation and Science Center. Retrieved from http://glovis.usgs.gov/
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