a Now at Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Drive Rochester, N.Y. 14623-5604 b Also at George Mason University, Department of Geography and Geoinformation Science Suite 2400 Exploratory Hall, 4400 University Drive, Fairfax, VA 22030 Retrieval of Sand Density from Hyperspectral BRDF Charles M. Bachmann ͳ,a , Andrei Abelev ʹ William Philpot ͵ Katarina Z. Doctor ͳ,b , Marcos J. Montes ͳ , Robert Fusina ͳ , Rong-Rong Li ͳ , Elena van Roggen Ͷ Naval Research Laboratory, 1 Remote Sensing Division, and 2 Marine Geosciences Division 4555 Overlook Ave., SW, Washington, D.C. 20375, USA 3 Cornell University, School of Civil and Environmental Engineering, 220 Hollister Hall, Ithaca, NY, 14850 4 Marine Information Resources Corporation, Ellicott City, MD Abstract: )n past work ͳ , we have shown that density effects in hyperspectral bi-directional reflectance function ȋBRDFȌ data are consistent in laboratory goniometer data, field goniometer measurements with the NRL Goniometer for Portable (yperspectral Earth Reflectance ȋGOP(ERȌ, and airborne CAS)-ͳͷͲͲ hyperspectral imagery. Density effects in granular materials have been described in radiative transfer models ʹ,Ͷ,ͷ , and are known, for example, to influence both the overall level of reflectance as well as the size of specific characteristics such as the width of the opposition effect in the BRDF. (owever, in mineralogically complex sands, such as coastal sands, the relative change in reflectance with density depends on the composite nature of the sand ͵ . This paper examines the use of laboratory and field hyperspectral goniometer data and their utility for retrieving sand density from airborne hyperspectral imagery. We focus on limitations of current models to describe density effects in BRDF data acquired in the field, laboratory setting, and from airborne systems. Key words: bidirectional reflectance distribution function ȋBRDFȌ, sand density, goniometer, hyperspectral, spectroscopy, opposition effect, radiative transfer 1. INTRODUCTION Models describing radiative transfer in disordered media have been developed in the past ʹ,Ͷ,ͷ . Approximate solutions to the radiative transfer equations have been described in a number of publications by (apke ʹ,͸,͹,ͺ,ͻ,ͳͲ . These models have been used to describe the bi-directional reflectance distribution ȋBRDFȌ of both planetary bodies as well as observations of some terrestrial data with success, especially in planetary astronomy. Coastal sediments, however, represent a particular challenge for these models because of the complex nature of the mineral mixtures, the presence of water in pore space, on the surface which changes with time through the tidal cycle, and variations in other significant parameters such as grain size distributions, which can vary substantially even on relatively small scale in some coastal regions. Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery XX, edited by Miguel Velez-Reyes, Fred A. Kruse, Proc. of SPIE Vol. 9088, 908807 · © 2014 SPIE · CCC code: 0277-786X/14/$18 · doi: 10.1117/12.2050682 Proc. of SPIE Vol. 9088 908807-1 Downloaded From: http://www.spiedl.org/ on 05/15/2015 Terms of Use: http://spiedl.org/terms