MISR abstract
Prabal Nandy, Kurtis J. Thome, and Stuart F. Biggar (2000). Sensitivity analysis of a CCD-based camera system for the retrieval of bidirectional reflectance distribution function for vicarious calibration. Proceedings of the SPIE - The International Society for Optical Engineering: Imaging Spectrometry VI. 4132, 279-289.
The University of Arizona, Optical Sciences Center, RemoteSensing group is involved with the vicarious calibration of satellite sensors in support of NASA's Earth Observing System (EOS) program. Sensor calibration coefficients are calculated bycomparing sensor DN values to top of the atmosphere (TOA)radiance values, calculated from radiative transfer code outputbased on measurements of site spectral reflectance andatmospheric parameters at a selected test site. The bidirectionalreflectance distribution function (BRDF) relating the angularscattering of a given beam of incident radiation, is an importantfactor in these radiative transfer calculations. The inclusion ofBRDF data into RTC calculations improves the level of accuracy ofthe vicarious calibration method by up to 5% over some targetsites. BRDF data is also valuable in the validation of Multi-Angle Imaging Spectroradiometer (MISR) data sets. The Remote Sensing Group has developed an imaging radiometersystem for ground-based measurements of BRDF. This system relieson a commercially-available 1024- by 1024-pixel silicon CCDarray. Angular measurements are accomplished with a 8-mm focallength fisheye lens that has a full 180-degree field of view.Spectral selection is through four interference filters centeredat 470, 575, 660 and 835 nm, mounted internally in the fisheyelens. This paper discusses the effect of calibration errors inthis camera system on the retrieval of Hapke/Jacquemonde surfaceparameters from modelled BRDFs. The effect of these retrievedBRDFs on vicarious calibration results is discussed. Dataprocessing schemes for the retrieval of these parameters fromBRDF camera data sets are described. Based on these calculations,calibration requirements for digital camera BRDF-retrievalsystems are presented.