Change Detection
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A second change detection example using multitemporal Landsat MSS images is presented to further show the potential use of remotely sensed satellite data to study the desert environment, map eolian erosion, and monitor global change. The images were used to detect vegetation changes in the desert; they cover parts of extreme southwestern Arizona, including the area around Yuma. The first pair of Landsat MSS images detects changes between a wet (April 4) and dry (July 1) season in 1992. Chavez and MacKinnon (1994) found that a radiometrically calibrated visible band is better to detect changes in desert vegetation than a vegetation index (such as the NDVI). Landsat MSS band 5 (red spectral band) for the two dates is shown along with the corresponding digital change image. The second pair of images below are the Landsat MSS band 5 and their corresponding digital change image for the same area; however, these images were recorded on February 24, 1981 (dry year) and February 26, 1984 (wet/El Nino year). In both sets of images the dark tones in the change image represent areas that were more vegetated during the wet season/year and the brighter tones are areas that were more vegetated during the dry season/year (mostly agricultural areas/crops).
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