Influence of irradiance on bidirectional reflectance factor measurements

Pedro Neves da Silva Filho; Jose Carlos Nev Epiphanio

doi:10.1117/12.161548

15 November 1993 Influence of irradiance on bidirectional reflectance factor measurements

Pedro Neves da Silva Filho, Jose Carlos Nev Epiphanio

Proceedings Volume 1938, Recent Advances in Sensors, Radiometric Calibration, and Processing of Remotely Sensed Data; (1993) https://doi.org/10.1117/12.161548
Event: Optical Engineering and Photonics in Aerospace Sensing, 1993, Orlando, FL, United States

Abstract

In field studies involving radiometry the irradiance variation is an important factor affecting measurements. There are tradeoffs between methods for obtaining the reflectance of a target. A widely spread method of field radiometry is the one where an instrument measures a reference panel and then the target. In some cases, for one measurement of reference, many target measurements may be taken, and between the target and the reference measurements irradiance may change. This change can dramatically affect the detected signal, and consequently the bidirectional reflectance factor. This paper reports an experiment conducted to study the influence of irradiance variations on the determination of the bidirectional reflectance factor of a target. For a clear day the bidirectional reflectance factor was measured at different time-interval rates. Irradiance was measured at a one second rate. The time spent on three different reflectance measurements method was evaluated at first. Results showed that for a unfavorable situation, in which a substitution method was tested, the error introduced with a 180 seconds interval between target and reference measurements is of the same magnitude as the nominal error of the radiometer intercalibration. For an unfavorable day, in which there were clouds, error as great as 16% can be introduced in the BRF measurements.

Citation Download Citation

Pedro Neves da Silva Filho and Jose Carlos Nev Epiphanio "Influence of irradiance on bidirectional reflectance factor measurements", Proc. SPIE 1938, Recent Advances in Sensors, Radiometric Calibration, and Processing of Remotely Sensed Data, (15 November 1993); https://doi.org/10.1117/12.161548

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