CLASSIFICATION OF A LANDSAT-TM IMAGE WITH THE SPECTRAL MIXTURE
ANALYSIS UNDER THE APPLICATION OF FIELD SPECTROSCOPY
Beate Eibl, Heike Bach, Wolfram Mauser
Institute of Geography, University of Munich
Luisenstr. 37, D-80333 Munich, Germany
Tel.: +49-89-5203 335, Fax.: +49-89-5203 321
Email: b.eibl@iggf.geo.uni-muenchen.de
Commission VII, Working group |
KEY WORDS: Remote sensing, Classsification, LANDSAT, Spectroscopy,
Spectral mixture analysis, Bare soil surfaces, Geology
Abstract: A LANDSAT-TM-5 image from a desert area was classified with the spectral mixture
analysis. The endmember for the spectral unmixing were selected by means of field spectroscopy
By this approach 98% of the image could be classified with an average rms of 0.7%. The results of
the linear unmixing were confirmed by ground truth data.
Kurzfassung: Ein LANDSAT-TM-5-Bild aus der Libyschen Wüste wurde mit der Linearen Entmi-
schung klassifiziert. Die Endmember für die Entmischung wurden aus der Analyse von Feldspektro-
meter-Messungen ausgewählt. Mit dieser Methode konnten 98 ?6 des Bildes mit einem durch-
schnittlichen RMS von 0.796 klassifiziert werden. Die Ergebnisse wurden anhand von Gelándedaten
überprüft.
1 INTRODUCTION
Field spectroscopy and LANDSAT-TM-5 are two remote
sensing systems which cover the same wavelength range
from 0.4 to 2.4um, however, they differ in the spatial and
spectral resolution. In this study a LANDSAT-TM-5 image
was classified with the spectral mixture analysis and field
spectra were used for the selection of the endmembers.
Their high resolution of 2 - 6nm is usefull for determining
very small differences in the spectral signatures of the
surfaces.
This combination of datas was applied to the charac-
terization of bare soil surfaces particularly for loose sedi-
ments. The study area was Wadi Rayan southwest of Cairo
in the Libyan desert. It is an escarpment surrounded by
pediments. A broad dune belt covers the center of the
807 SAND
< sd
— i EA P^
8 60 7
J N
S N
Q 40—
©
= t
= 20—
o
à -
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0 I | 1 | 1 | 1 | Ï |
0.4 0.8 1.2 1.6 2.0 2.4
wavelength (um)
study area and several longitudinal dunes are located be-
tween the escarpments. Allmost all surfaces are covered
by weathered material. The bedrock is limestone (mainly
marine) full of the leading fossil Nummulite. In between
there are layers of clay, sand and flint. A detailled ground
check was carried out in October 1993 and 96 spectra of
the soil surfaces were acquired using a SIRIS spec-
trometer. The LANDSAT-TM image was acquired on
20.9.1993. The direct comparison of the data (spectro-
meter and LANDSAT-TM) requires conversion of the data
into absolute reflectance. Therefore, the processing of the
LANDSAT-TM image includes an atmospheric correction
by the radiative transfer code LOWTRAN-7 and a correc-
tion of the adjacency effects by a weighted filterbox (BACH
& MAUSER, 1994). For the field spectra there is no
influence of the atmosphere due to the acquisition method.
80 — NUMMULITIC
LIMESTONE
60 = ap Were day
pour FS.
40 —
20 77
0 I | I | I | 1 | ï
0.4 0.8 1.2 1.6 2.0 24
wavelength (um)
Fig. 1: Comparison of the measured field spectra with the calibrated data of the LANDSAT-TM bands 1 - 5 and 7 from the
surrounding of the selected spots
226
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996
