Orbital imagery TM/LANSAT-5 were treated by digital techniques aiming to evaluate the utility of this tool in soil surveys. The studied area has about 96 km² and is part of the Brigida River basin, in the Sertão region of Pernambuco State, Brazil, limited by UTM coordinates of 428,000 to 420,000 mE and 9,074,000 to 9,062,000 mN. The use of RGB transformations of the visible and infrared imagery, along with WFM contrast techniques, algebraic programs of the ERDAS, version 7.4, and field informations allowed a better mapping of the soil units. The results showed that digital image processing with field support is useful for soil surveys at the reconnaissance level. The most useful colored compositions (RGB) of the TM bands, for soil mapping purposes in the studied area, were 1-3-5 and 4-5-7.
soil mapping; TM/LANDSAT; image processing
