738,
aise.
ish
ntliga
gra-
130.
reas
al
graphs.
ift
cal
- 2163 -
SPECTRAL SIGNATURES OF GEOLOGICAL LINEATIONS ON LANDSAT
IMAGERY
Anne-Marie Martin
Lecturer - Photointerpretation for Geologists, Geologisches
Institut/Geotechnik, Ruhr Universitat Bochum
Introduction
"The word "signature," by definition, refers in general to a
distinguishing characteristic. In remote sensing, a "spectral
signature" of a feature comprises a set of values for the. re-
flectance or the radiance of the feature, where each value
corresponds to the reflectance or radiance averaged over a dif-
ferent, well defined, wave-length interval." (Manual of Remote
Sensing, p. 258) However, this criterion is redefined further
as "quantitative measurement of the properties of an object at
one or several wave-length intervals." (Manual of Remote Sen-
sing, p. 2104)
Due to the confusion occasioned by the above illustrated differ-
ences in terminology, for the purposes of this presentation a
"spectral signature" will be considered as a photo-lineation
appreciable on LANDSAT imagery, and presumably relating to
geology. (HOPPE 1974)
Definition
The terms "linear" and "lineament" have been used in photointer-
pretation of aerial photographs and may be defined as:
linear lines of uncertain origin which are determined on
air photographs and/or other imagery
lineament linear features known on the ground; by extension
those discovered in the course of field-work.
(ISACHSEN et al. 1972)
In the broadest sense a "photo-lineation" may be considered as
any extent of linears appearing on imagery, and may therefore
relate to features other than geology. Therefore, a composite
term is used here - "geological lineations" - indicating that
the discussed features are not lines of vegetation, highways,
valleys or strcam beds, etc. The linears which have been mapped
from LANDSAT imagery are considered to represent geological linea-
ments.
Geological Formations
In Geology, linears distinguished on aerial photographs are
relatively simple to define and represent often tectonic linea-
ments, lithological boundaries, faults and fracture zones. This
fact has often been used to locate ores, ground water reserves,
building and road materials, etc. Remote sensing has provided
a broader view of known areas and permits surveying and mapping
of previously unknown formations, even in an area as well field-
checked as the Federal Republic of Germany. (ADLER 1978; GÜNTHER
1978; HOPPE 1974; KRONBERG 1974; REUL 1975, 1974; REEVES et al.
1975; STREIT 1977)