title: Estimation of spectral distribution of sky radiance using a commercial digital camera.
abstract: Methods for estimating spectral distribution of sky radiance from images captured by a digital camera and for accurately estimating spectral responses of the camera are proposed. Spectral distribution of sky radiance is represented as a polynomial of the wavelength, with coefficients obtained from digital RGB counts by linear transformation. The spectral distribution of radiance as measured is consistent with that obtained by spectrometer and radiative transfer simulation for wavelengths of 430-680 nm, with standard deviation below 1%. Preliminary applications suggest this method is useful for detecting clouds and studying the relation between irradiance at the ground and cloud distribution.
authors.forename: Masanori
authors.initials: M
authors.lastname: Saito
authors.forename: Hironobu
authors.initials: H
authors.lastname: Iwabuchi
authors.forename: Isao
authors.initials: I
authors.lastname: Murata