Spectrodirectional investigation of a geometric-optical canopy reflectance model by laboratory simulation
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Date
2017
Authors
Stanford, Adam Christopher
University of Lethbridge. Faculty of Arts and Science
Journal Title
Journal ISSN
Volume Title
Publisher
Lethbridge, Alta : University of Lethbridge, Dept. of Geography
Abstract
Canopy reflectance models (CRMs) can accurately estimate vegetation canopy
biophysical-structural information such as Leaf Area Index (LAI) inexpensively using
satellite imagery. The strict physical basis which geometric-optical CRMs employ to
mathematically link canopy bidirectional reflectance and structure allows for the tangible
replication of a CRM's geometric abstraction of a canopy in the laboratory, enabling
robust CRM validation studies. To this end, the ULGS-2 goniometer was used to obtain
multiangle, hyperspectral (Spectrodirectional) measurements of a specially-designed
tangible physical model forest, developed based upon the Geometric-Optical Mutual
Shadowing (GOMS) CRM, at three different canopy cover densities. GOMS forwardmodelled
reflectance values had high levels of agreement with ULGS-2 measurements,
with obtained reflectance RMSE values ranging from 0.03% to 0.1%. Canopy structure
modelled via GOMS Multiple-Forward-Mode (MFM) inversion had varying levels of
success. The methods developed in this thesis can potentially be extended to more
complex CRMs through the implementation of 3D printing.
Description
Keywords
canopy reflectance models , geometric-optical methods , goniometer , physical computational forest simulations , remote sensing , spectrodirectional data sampling