The term "remote sensing" broadly refers to any sensing from afar, such as vision and hearing. In practice however the term usually means satellite or aerial imaging of the earth.
|NDVI -- Normalized Difference Vegetation Index reveals vegetation vigor. Red and orange indicate greater amounts of vegetation. The index compares radiance in the red and infrared bands. Image taken from 65,000ft by a U2 spy plane on July 3, 1997 using an AVIRIS hyperspectral sensor. The main red-orange strip running up the middle is the forested foothills between Coal Creek Canyon and El Dorado Canyon in Colorado. The riparian areas, also with strong amounts of vegetation can be seen branching up and to the left.|
From the greek: hyper = many or much; spectra = light. Refers to sensing and use of light information in many tens or hundreds of distinct bandwidths of light.
|Automatic extraction of quartzite areas around Coal Creek Canyon. 224 bands of AVIRIS hyperspectral data were used to produce the first 25 principal components. A matched filter than ranked the principal components based on selected quartzite training areas. Red indicates areas of quartzite. The black line traces the actual areas of quartzite. The false negatives are due to heavy vegetation cover or solar shading.|