Universität zu Köln

Burkart, Andreas, Aasen, Helge ORCID: 0000-0003-4343-0476, Alonso, Luis ORCID: 0000-0002-8221-5739, Menz, Gunter, Bareth, Georg and Rascher, Uwe ORCID: 0000-0002-9993-4588 (2015). Angular Dependency of Hyperspectral Measurements over Wheat Characterized by a Novel UAV Based Goniometer. Remote Sens., 7 (1). S. 725 - 747. BASEL: MDPI. ISSN 2072-4292

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Abstract

In this study we present a hyperspectral flying goniometer system, based on a rotary-wing unmanned aerial vehicle (UAV) equipped with a spectrometer mounted on an active gimbal. We show that this approach may be used to collect multiangular hyperspectral data over vegetated environments. The pointing and positioning accuracy are assessed using structure from motion and vary from sigma = 1 degrees to 8 degrees in pointing and sigma = 0.7 to 0.8 m in positioning. We use a wheat dataset to investigate the influence of angular effects on the NDVI, TCARI and REIP vegetation indices. Angular effects caused significant variations on the indices: NDVI = 0.83-0.95; TCARI = 0.04-0.116; REIP = 729-735 nm. Our analysis highlights the necessity to consider angular effects in optical sensors when observing vegetation. We compare the measurements of the UAV goniometer to the angular modules of the SCOPE radiative transfer model. Model and measurements are in high accordance (r(2) = 0.88) in the infrared region at angles close to nadir; in contrast the comparison show discrepancies at low tilt angles (r(2) = 0.25). This study demonstrates that the UAV goniometer is a promising approach for the fast and flexible assessment of angular effects.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Burkart, Andreas UNSPECIFIED UNSPECIFIED UNSPECIFIED Aasen, Helge UNSPECIFIED orcid.org/0000-0003-4343-0476 UNSPECIFIED Alonso, Luis UNSPECIFIED orcid.org/0000-0002-8221-5739 UNSPECIFIED Menz, Gunter UNSPECIFIED UNSPECIFIED UNSPECIFIED Bareth, Georg UNSPECIFIED UNSPECIFIED UNSPECIFIED Rascher, Uwe UNSPECIFIED orcid.org/0000-0002-9993-4588 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-417582
DOI:	10.3390/rs70100725
Journal or Publication Title:	Remote Sens.
Volume:	7
Number:	1
Page Range:	S. 725 - 747
Date:	2015
Publisher:	MDPI
Place of Publication:	BASEL
ISSN:	2072-4292
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Geosciences > Geographisches Institut
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language IMAGING SPECTRORADIOMETER MODIS; BIDIRECTIONAL REFLECTANCE; VEGETATION INDEXES; FIELD GONIOMETER; CHLOROPHYLL CONTENT; SPECTRAL INDEXES; ACQUISITION; RETRIEVAL; RADIATION; CANOPIES Multiple languages Environmental Sciences; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/41758