Using a multikernel least-variance approach to retrieve and evaluate albedo from limited bidirectional measurements

Citation
F. Gao et al., Using a multikernel least-variance approach to retrieve and evaluate albedo from limited bidirectional measurements, REMOT SEN E, 76(1), 2001, pp. 57-66
Citations number
17
Categorie Soggetti
Earth Sciences
Journal title
REMOTE SENSING OF ENVIRONMENT
ISSN journal
00344257 → ACNP
Volume
76
Issue
1
Year of publication
2001
Pages
57 - 66
Database
ISI
SICI code
0034-4257(200104)76:1<57:UAMLAT>2.0.ZU;2-7
Abstract
When a multikernel modelling approach is being applied to remotely sensed d ata, a new criteria - least variance of white-sky albedo selects semiempiri cal bidirectional reflectance distribution function (BRDF) kernel combinati ons better than the more conventional least-squares fitting criteria. The B RDF describes the scattering of light from surface as a function of illumin ation and view geometry. Semiempirical kernels are nonlinear geometric func tions derived from a simplification of physical models of scattering. These are combined linearly to fit observed bidirectional reflectance measuremen ts. White-sky albedo (bihemispherical reflectance) is the integral of direc tional reflectance for all viewing and illumination directions and is a tru e surface property. The variance of retrieved white-sky albedo is a functio n of the noises of measurement, the specific viewing and illumination geome try of the surface scattering measurements, and the number of observations used in the inversion. By selecting the kernel combination that provides th e least variance of white-sky albedo, our studies show that a more stable e stimate of white-sky and black-sky (directional-hemispherical) albedo is pr oduced. (C) 2001 Elsevier Science Inc. All lights reserved.