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<br />the variety of land-use categories present were defined by comparing the 1973 <br />photographs with updated ground information to locate areas that remained <br />virtually unchanged between 1973 and 1975. <br /> <br />Selection of the best Landsat MSS-band configuration for analysis of a <br />certain surface feature of interest is a function of many factors, including <br />the type of feature to be evaluated, the time of year, the atmospheric <br />conditions, and the quality of the imagery. Color-composite images (see <br />Glossary) tend to enhance the various features displayed on the imagery. <br />Color-composite images generally provide photointerpreters with more usable <br />information for the majority of applications than is available from single- <br />band black-and-white images. <br /> <br />For example, on the August 24, 1975, image (fig. 4), selected features <br />appear as follows: <br /> <br />1. Clouds--white with a corresponding shadow on the northwest side. <br /> <br />2. Snow--white, but with no shadow. <br /> <br />3. Water--black. <br /> <br />4. Irrigated or lush vegetation--bright pink or red. <br /> <br />5. Dryland agriculture--brown and green areas with defined patterns. <br /> <br />6. Rangeland--blue or green with no defined patterns. <br /> <br />7. Sparse vegetation (barren land)--shades varying from blue or gray to <br />almost white. <br /> <br />8. Conifers--dark red or brown to almost black. <br /> <br />9. Deciduous vegetation--various shades of red. <br /> <br />The following land-use categories were selected for determination by <br />photographic-interpretation techniques: <br /> <br />Levd I Levd II <br /> <br />Urban--------- Residential and commercial. <br /> <br />Transportation and utilities. <br /> <br />Barren land--- Strip mines. <br /> <br />Urban areas in the Yampa River basin are small. The largest towns in the <br />basin are Craig and Steamboat Springs in Colorado (fig. 1). Estimated popu- <br />lations in 1975 were 8,DDO for Craig and 5,900 for Steamboat Springs. A <br />snow-covered image is generally best for determining locations of urban cen- <br />ters and major highways because of the contrast between the snow and the <br /> <br />10 <br />