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Land Cover, Baltimore County

High resolution land cover dataset for Baltimore County, MD. Seven land cover classes were mapped: (1) tree canopy, (2) grass/shrub, (3) bare earth, (4) water, (5) buildings, (6) roads, and (7) other paved surfaces. The minimum mapping unit for the delineation of features was set at 8 square meters. The primary sources used to derive this land cover layer were color infrared aerial imagery acquired in 2007 as part of the National Agricultural Imagery Program (NAIP), a normalized Digital Surface Model (nDSM) derived from 2005 LiDAR data, LiDAR intensity data resulting from the 2005 acquisition, building footprints, road polygons, and water polygons. This land cover dataset is considered current as of August, 2007. Object-based image analysis techniques (OBIA) were employed to extract land cover information using the best available remotely sensed and vector GIS datasets. OBIA systems work by grouping pixels into meaningful objects based on their spectral and spatial properties, while taking into account boundaries imposed by existing vector datasets. Within the OBIA environment a rule-based expert system was designed to effectively mimic the process of manual image analysis by incorporating the elements of image interpretation (color/tone, texture, pattern, location, size, and shape) into the classification process. A series of morphological procedures were employed to insure that the end product is both accurate and cartographically pleasing. No accuracy assessment was conducted, but the dataset was subject to a thorough manual quality control. Over 16,000 corrections were made to the classification.