How Can Getting Farther Away from Earth Help Us See It More Clearly?
ESU101  Multispectral Imaging

Infrared imaging is only one example of using wavelengths other than visible light to gather information about Earth. Most satellites today measure energy at many wavelengths. This is called multispectral imaging. Images taken at different wavelengths can be combined to make composite images by displaying the image for each wavelength as red, green, or blue in the final image. These composite images result in color patterns that can be used to identify surface features.

This simulation shows images of San Francisco, California at three different wavelengths. Bright areas show higher amounts of energy; darker areas show lower amounts of energy. You can display each image in red, green, or blue light, then generate a false-color composite image for any color combination.

Look for these features in the image: Water appears dark around land in the center of the image. Blocky patterns represent buildings and streets. Park areas on both sides of the Golden Gate Bridge (the thin line across the water in upper left of image) are covered with vegetation.

  !   After the page has fully loaded, click the R (red), G (green), and B (blue) buttons to assign a different color to the images for each wavelength. Click Show Composite to combine the information into one color image.
Multispectral images courtesy of MITI, ERSDAC, JAROS,
and the U.S./Japan ASTER Science Team

  !   Change the color assignments to generate several different composites. Explore how features described in the text above can be identified in various composites.

Each composite you generate shows information about all three wavelengths. Combining the images in different ways helps identify specific surfaces such as water, buildings, and vegetation.

6. If a near-infrared image of vegetation were assigned to the red channel of a false color image, how would the vegetation appear?


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