Week 11: Using Satellite Data to Investigate Deforestation

Working with multispectral data in ImageJ

In this section, you will learn how satellites and aircraft use a single black and white camera with colored filters to capture data that can be used to re-create both natural and false color images.

The Landsat Program

• Download and unzip the LANDSAT Image Archive.zip file into the Week 3 directory or folder you created on your computer.
LANDSAT Image Archive.zip (Zip Archive 4MB Jan19 10)
• Choose File > Import > Image Sequence... to import the seven LANDSAT images, representing the seven Thematic Mapper bands into ImageJ as a stack.
Show me more about the seven TM bands.
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Image courtesy of NASA
• Move forward and backward through the stack. The label of each slice lists the TM band it represents. These images show the area around the community of Green River, south of Tucson, Arizona. Do you see signs of mining activity, agriculture, and recreation in the images?
• After you have explored the images, close the stack.

You are going to use these images to re-create a "true color" version of the scene by combining three bands that represent what is seen in red, green, and blue wavelengths.

• Open, in order, the Band 3 (red), Band 2 (green), and Band 1 (blue) images and stack them. (Click the Stacks Menu button and choose Images to Stack.)
• Choose Image > Color > Make Composite.
• In the Make Composite dialog box, set the Display Mode to Composite and click OK. The resulting image - called a 321 composite, since it assigned bands 3, 2, and 1 to the red, green, and blue channels - is a true color image that approximates what the scene would look like to your "eyes in the sky".
  Show me a 321 true color image.
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• Use this technique to produce a false color composite image, assigning different bands to the red, green, and blue color channels. (Hint: 432 images are often used to highlight vegetation in red - try it!)
  Show me a 432 false color image.
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• Create your own false color image of this scene and save it to your Week 3 directory. Choose Image > Image Type > RGB Color and save the resulting image as a JPEG file. Use the channel assignments and your initials in your file name.

Perhaps refer to this compositor for understanding satellite images (from NASA and Landsat 7.)

Create Your Own Composite Image

Larry, I just lifted this from the discussion page so you could see the assignment. The Image Gallery that I found is here:

Index of Landsat Images
Create a new discussion thread and post:

1. The composite image you created, along with a description of the three spectral bands you chose, and what features of the image were highlighted by the combination of spectral bands you chose. Your image should be in JPG format
2. The name of the image you selected from the Landsat Event gallery, along with a description of the spectral bands used to create the image, and what land features were highlighted by those spectral bands.
3. Share one or more ideas about how you might incorporate the use of these multispectral images into your teaching. If you're having trouble coming up with ideas, pose a question to others in your discussion group asking for suggestions specific to your images.

   Resources

4. The Landsat Program
5. Landsat Image Compositor
6. USGS Landsat Global Visualization Viewer
7. USGS EarthExplorer