Quality and use of ERTS radiometric information in geologic applications

Some techniques are described for making full use of the data contained in an ERTS MSS image. Only about one-fourth of the data in a single band can be displayed at one time on a black and white image; therefore, when all four bands are considered, only about 7% of the available data can be used by the interpreter. Selecting the proper subset of information for the photointerpreter is therefore a necessity. Ratio methods exclude the brightness information from the display. A field study in one area using a portable spectrometer has shown only fair correlation with ERTS radiometry after one normalization procedure. Plots of brightness of test areas with sun angle show discrepancies. Plots of ratios show discrepancies of lesser magnitude, although the error limits are large.