Remember Me
Forgot your username?
Forgot your password?
Login
LEO
Search ...
Sidebar
×
Main menu sidebar
LEO
People
Projects
Publications
Journal papers
Conference papers
PhD & Master thesis
Technical reports
Software/Data
ARTMO
About Us
Presentation
Organization
Facilities
Instruments
HyperSense Instruments
LEO
People
Projects
Publications
Journal papers
Conference papers
PhD & Master thesis
Technical reports
Software/Data
ARTMO
About Us
Presentation
Organization
Facilities
Instruments
HyperSense Instruments
SCOPE-Based Emulators for Fast Generation of Synthetic Canopy Reflectance and Sun-Induced Fluorescence Spectra
Progress in advanced radiative transfer models (RTMs) led to an improved understanding of reflectance (R) and sun-induced chlorophyll fluorescence (SIF) emission throughout the leaf and canopy. Among advanced canopy RTMs that have been recently modified to deliver SIF spectral outputs are the energy balance model SCOPE and the 3D models DART and FLIGHT. The downside of these RTMs is that they are computationally expensive, which makes them impractical in routine processing, such as scene generation and retrieval applications. To bypass their computational burden, a computationally effective technique has been proposed by only using a limited number of model runs, called emulation. The idea of emulation is approximating the original RTM by a surrogate machine learning model with low computation time. However, a concern is whether the emulator reaches sufficient accuracy. To this end, we analyzed key aspects of emulator development that may impact the precision of emulating SCOPE-like R and SIF spectra, being: (1) type of machine learning, (2) type of dimensionality reduction (DR) method, and (3) number of components and lookup table (LUT) size. The machine learning family of Gaussian processes regression and neural networks were found best suited to function as emulators. The classical principal component analysis (PCA) remains a robust DR method, but the number of components needs to be optimized depending on the complexity of the spectral data. Based on a small Latin hypercube sampling LUT of 500 samples (70% used for training) covering a selection of SCOPE input variables, the best-performing emulators can reconstruct any combination for the selected SCOPE input variables with relative errors along the spectral range below 2% for R and 4% for SIF. That is sufficient for a precise reconstruction for the large majority of possible combinations, and errors can be further reduced when increasing LUT size for training. As a proof of concept, we imported the best-performing emulators into a newly developed Automated Scene Generator Module (A-SGM) to generate a R and SIF synthetic scene of a vegetated surface. Using emulators as alternative of SCOPE reduced the processing time from the order of days to the order of minutes while preserving sufficient accuracy.
Autors:
Verrelst, J., Rivera-Caicedo, J.P., , Muñoz-Marí, J., Camps-Valls, G., Moreno, J.
Url link:
http://www.mdpi.com/2072-4292/9/9/927
Journal:
Remote Sensing
Year:
2017
Powered by ChronoForms - ChronoEngine.com
Powered by ChronoConnectivity - ChronoEngine.com
You are here:
Home
Publications
Journal papers