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.