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were determined by an algorithm that utilizes a moving 
window of 3 by 3 pixels to select distinct training fields 
in an unsupervised manner. Each pixel was then assigned to 
respective spectral class with the ELAS maximum likelihood 
program (MAXL31). The pixels were geographically refer 
enced to the UTM grid using a least squares fit to a series 
of common control points taken from USGS's 7% minute 
topographic quadrangels. 
Extensive site surveys were then used to determine the 
land cover associations for the different spectral classes. 
This ground truthing effort was directed toward training 
sites that were selected from aerial photography, ortho 
photo quads and similar imagery. The resultant eight 
land cover classes generally followed the USGS level I 
categories (Table 1). No attempt was made to classify any 
subareas within urban areas, however, the forests were 
subdivided into the level II classes of deciduous, ever 
green and mixed. 
The classified data for the nine scenes were then mathe 
matically mosaicked into a single file. This data set was 
resampled into square cells, 63.5 meters on a side. Color 
separations for a general land cover map of the State at a 
scale of 1:500,000 were generated from the data set. The 
file comprises a major component of the state-wide 
geographical information system that has combined several 
other variables. Although more rigorous ground truthing 
procedures and multi-temporal data sets have been used for 
more detailed analysis in selected sites, the file has met 
the basic needs for state-wide coverage and has created a 
great deal of interest in Landsat processing within the 
State. 
USGS LAND USE AND LAND COVER MAPS 
The USGS land use and land cover mapping program represents 
the first attempt to systematically inventory the use of 
land in the United States (Place 1977). The program 
utilizes high altitude photography to determine level II 
land use and land cover polygons for the USGS 1:250,000 
scale basemaps. A major component of the program has been 
the generation of digital files for these maps. Potentially 
these files represent a major data base for computer 
mapping and geographical analysis. 
South Carolina became actively involved in the USGS program 
in 1978 when its Coastal Zone Management Plan mandated the 
inventory and mapping of land use. At that time the USGS 
provided the State with its Geographical Information 
Retrieval and Analysis System (GIRAS) and digitized polygon 
files for the James Island and Savannah quadrangles (Fig. 2). 
The Graphics Division at the University of South Carolina 
digitized parts of three other maps and then generated the 
combined polygon files required for the production of the 
Coastal Zone Land Use and Land Cover Map that covered an 
eight county area (Cowen et al 1979). 
Over the next couple of years the USGS furnished the