Journal article

A Two-Phase Parameter Estimation Method for Radiative Transfer Problems in Paper Industry Applications

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Publication Details

Author list: Edström, Per

Publication year: 2008

Start page: 927

End page: 951

Number of pages: 25

ISSN: 1741-5977

DOI: http://dx.doi.org/10.1080/17415970802080066

View additional information: View in Web of Science


Abstract

A two-phase method for estimation of the scattering and absorption coefficients and the asymmetry factor (sigma_s, sigma_a and g) in the radiative transfer problem is presented. The first phase parameterizes sigma_s and sigma_a through g via a simplified model and performs - at a relatively low cost - a scalaroptimization over g. It is shown that this gives such a good starting point that the second phase can be accurately performed by a simple Gauss-Newton method. It is also shown that a part of the first phase can be used on its own when only sigma_s and sigma_a are wanted, and it is noted that this gives higheraccuracy than the commonly used Kubelka-Munk method when using standardized paper industry reflectance factor measurements.The parameter estimation problem is shown to be non-trivial and ill-conditioned, and its character is analyzed. It is discussed that standard optimization methods are so sensitive to the choice ofstarting point for this problem that it is hard to find a starting point that gives convergence at all. The new two-phase method is illustrated by application to relevant paper industry problems, and efficiency and sensitivity measures are given.


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