An Accuracy Assessment of 1997 Landsat Thematic Mapper Derived Land Cover for the Upper San Pedro Watershed (U.S./Mexico)
High-resolution airborne color video data were used to evaluate the accuracy of a land cover map of the upper San Pedro River watershed, derived from June 1997 Landsat Thematic Mapper data. The land cover map was interpreted and generated by Instituto del Medio Ambiente y el Desarrollo Sustentable del Estado de Sonora (IMADES), Hermosillo, Sonora and supplied to the Arizona Remote Sensing Center at the University of Arizona for evaluation. Map pixel size had been increased from 30 to 60 meters to match the 1973, 1986, and 1992 North American Landscape Characterization (NALC) land cover maps produced from Landsat MMS data.
The airborne color video data included six flight lines acquired 2-5 May 1997 over the San Pedro watershed in the U.S. GPS time and coordinate information encoded on the video tapes were used to generate GIS point coverages of video frames covering the upper San Pedro. A total of 527 video sample points were drawn randomly from a subset of 4567 frames falling on areas of uniform cover classes at least 180 meters square. Sample points were stratified by cover class area, with a minimum sample of 24 points for classes of small areal extent. The Water class was extremely rare covering less than 0.1% of the study area) and was excluded from video data analysis for lack of data. Video sample points were reviewed by an experienced interpreter who assigned land cover class labels based on available descriptions. Map and video labels were compared to generate a classification error matrix, which produced an overall map accuracy of about 72%.
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