A new dual-beam technique for precise measurements of spectral reflectance in the field

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Description/Abstract

Field spectral measurements made using the single - beam method often include errors due to variation in illumination between measurement of the target and the
reference (panel or cosine -corrected receptor). Although the dual-beam method avoids these errors, it introduces greater complexity due to the need to intercalibrate the two sensor heads used, and it is significantly more expensive. This paper describes an alternative dual-beam method which uses a neural network to estimate the complete irradiance spectrum from measurements made in 7 narrow bands. These narrow band measurements of irradiance may be made with a simple
filter-based radiometer, thus avoiding the expense and complexity of a second spectroradiometer. The new technique has been tested using irradiance spectra from both continental and maritime locations.