So far, only signature curves based on the means of the
reflectance factors have been shown. However, a variation of
the reflectance of even the same object which can be caused by
a large number of factors can be expected (11). This variance
seems to be very high in the near IR (figure 10) but this should be
proved by comparing the coefficients of variation.
It becomes clear, however, in figure 11 that the coefficients
are not considerably higher in the near IR compared with those
in the visible part of the spectrum. Nevertheless, a drastic
change of the coefficients can be observed for a mature beech
stand. This is due to the fact that the crown size of these
beeches could not be integrated by the instantaneous field of
view, which is to say, the light and shadow-patterns of the 2
individual crowns cannot be integrated by the IFOV of 2 x 2 m*.
In addition, the shadow patterns of the crowns are not brightened
by the scattering light as it is the case in the visible part of
the spectrum.
High variances of the reflectance factors make it difficult to
recognize objects because of their reflection behaviour. As shown
in figure 12 this variance can be largely reduced by selecting
a suitable ground resolution which can be obtained either by
smocthing the pixels of the imagery considered or by using a
higher flight level.
Since it is not possible to compare several hundred signatures
standardized as described in this paper but each of them obtained
under different conditions we need a data management system which
enables us to work with a large quantity of data. Such a data
bank management system is going to be established at the computer
center of the University of Freiburg.
Literatur Cited
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tation, Proceedings IUFRO S 6.05, Oslo, 1976
/2/ Modular Multispectral Scanner (vas) Folder I Technical Proposals, Ann-
Arbor, Michigan, April 1974
/3/ H.J. Boehnel: Bestimmung spektraler Signaturen von bewachsenen Oberflächen
durch radiometrische Bodenmessungen (Realisierung und Probleme) *)
/4/ Fischer W.: Zur Signifikanz von spektralen Signaturen bewachsener Ober-
flüchen im Bereich 4oo - 1100 Nanameter +)
/5/ Kadro, A.: Spektrale Reflexion land- und forstwirtschwaftlicher Kulturen
während der Vegetationsperiode *)
/6/ Reichert P.G.: Der Multispektralscanner als Instrument der Signaturforschung +)
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talen M^áS-Videodaten entsprechenden Strahldichte in den Spektralbereichen
1 mit 10, bzw. der den Daten aus dem Thermalbereich zuzuordnenden Tempe-
raturen (nicht veróffentlich)
/8/ Schrüder, M.: Ziele und Aufgaben des FlugzeugmeBprogrammes +)
/9/ Reichert P.: Vegetationskundliche Auswertung multispektraler Scannerauf-
zeichnungem Proceedings IUFRO S 6.05, Oslo 1976
/1o/ StátterR.: Einflu8 radiometrischer Parameter auf Fernerkundungsaufnahmen *)
/11/ Reichert P.G.: Einsatzmóglichkeiten des Multispektralscanners für land-
und forstwirtschaftliche Inventuren. *
*) Forschungsbericht W 78-04 des BM für Forschung und Technologie, 1978