Emulation as an Accurate Alternative to Interpolation in Sampling Radiative Transfer Codes

12/07/2020
by   Jorge Vicent, et al.
0

Computationally expensive Radiative Transfer Models (RTMs) are widely used to realistically reproduce the light interaction with the Earth surface and atmosphere. Because these models take long processing time, the common practice is to first generate a sparse look-up table (LUT) and then make use of interpolation methods to sample the multi-dimensional LUT input variable space. However, the question arise whether common interpolation methods perform most accurate. As an alternative to interpolation, this work proposes to use emulation, i.e., approximating the RTM output by means of statistical learning. Two experiments were conducted to assess the accuracy in delivering spectral outputs using interpolation and emulation: (1) at canopy level, using PROSAIL; and (2) at top-of-atmosphere level, using MODTRAN. Various interpolation (nearest-neighbour, inverse distance weighting, piece-wice linear) and emulation (Gaussian process regression (GPR), kernel ridge regression, neural networks) methods were evaluated against a dense reference LUT. In all experiments, the emulation methods clearly produced more accurate output spectra than classical interpolation methods. GPR emulation performed up to ten times more accurately than the best performing interpolation method, and this with a speed that is competitive with the faster interpolation methods. It is concluded that emulation can function as a fast and more accurate alternative to commonly used interpolation methods for reconstructing RTM spectral data.

READ FULL TEXT
research
04/14/2021

Five Degree-of-Freedom Property Interpolation of Arbitrary Grain Boundaries via Voronoi Fundamental Zone Octonion Framework

We introduce the Voronoi fundamental zone octonion interpolation framewo...
research
03/26/2018

Interpolation error of misspecified Gaussian process regression

An interpolation error is an integral of the squared error of a regressi...
research
12/07/2020

Gradient-based Automatic Look-Up Table Generator for Atmospheric Radiative Transfer Models

Atmospheric correction of Earth Observation data is one of the most crit...
research
05/18/2020

An Efficient Machine-Learning Approach for PDF Tabulation in Turbulent Combustion Closure

Probability density function (PDF) based turbulent combustion modelling ...
research
03/07/2023

Kernel interpolation of acoustic transfer functions with adaptive kernel for directed and residual reverberations

An interpolation method for region-to-region acoustic transfer functions...
research
11/18/2022

Neural Fields for Fast and Scalable Interpolation of Geophysical Ocean Variables

Optimal Interpolation (OI) is a widely used, highly trusted algorithm fo...
research
11/13/2020

Determinantal Point Processes Implicitly Regularize Semi-parametric Regression Problems

Semi-parametric regression models are used in several applications which...

Please sign up or login with your details

Forgot password? Click here to reset