title: Automated directional measurement system for the acquisition of thermal radiative measurements of vegetative canopies.
abstract: The potential for directional optical and thermal imagery is very large. Field measurements have been performed with a goniometer on which thermal instruments were attached. In order to reduce dynamical effects the goniometer was adjusted to run in automated mode, for zenith and azimuthal direction. Directional measurements were performed over various crops with increasing heterogeneity. The improvements to the goniometer proved successful. For all the crops, except the vineyard, the acquisition of the directional thermal brightness temperatures of the crops went successfully. The large scale heterogeneity of the vineyard proved to be larger then the goniometer was capable of. The potential of directional thermal brightness temperatures has been proven.
authors.affiliation: International Institute for Geo-Information Sciences and Earth Observation (ITC) / Hengelosestr. 99, P.O. Box 6, 7500 AA Enschede, the Netherlands; E-Mails:  Gieske@itc.nl  (A.G.);  tol@itc.nl  (C.T.);  verhoef@itc.nl  (W.V.);  b_su@itc.nl  (Z.S.).
authors.forename: Joris
authors.initials: J
authors.lastname: Timmermans
authors.forename: A S M
authors.initials: AS
authors.lastname: Ambro Gieske
authors.forename: Christiaan
authors.initials: C
authors.lastname: van der Tol
authors.forename: Wout
authors.initials: W
authors.lastname: Verhoef
authors.forename: Zhongbo
authors.initials: Z
authors.lastname: Su