International Archives of Photogrammetry and Remote Sensing, Vol. 32, Part 7-4-3 W6, Valladolid, Spain, 3-4 June, 1999
likelihood classifications with maximum likelihood tie
resolution and three standard deviations were used.
Training areas have been selected using as sole criterion the
human capability to discriminate among different colours of
each FCC. As an additional help to the classification process,
signature separability reports and scatterplots were used. A
great effort was made in order to create as many representative
classes for each approach as possible, so that the majority of the
pixels were classified as one of the available classes. It was not
always possible to use the same training areas for the
multispectral and the anisotropy approaches. The majority of
the classes created were the same, but the total class number and
the described objects varied a little.
Classification accuracy was assessed by comparing about 100
classified pixels with management maps of the Diimast
experimental farm and forest management maps. No
information was available for the privately owned farmland.
4. RESULTS
Using visual interpretation, only the complementarity
capabilities can be estimated. For evaluating the synergy effects,
a combined analysis of all mode D bands has to be performed.
4.1. Visual interpretation
The large landcover classes forest, agricultural areas, settlement
areas, water bodies and infrastructure are detectable with similar
accuracy in both FCCs. Nevertheless, due to the „structured“
impression of the „anisotropy“ FCC, the visual delineation of
settlements seems to be easier. The further differentiation of
these main landcover categories shows object-specific
advantages for the one or the other approach.
Fig. 9. Forest type discrimination: left „anisotropy“, right
„multispectral“ approach.
As far as the discrimination between the forest types is
concerned, the anisotropy approach does not provide a clear
visual discrimination. The multispectral approach provides
better results in this respect (Figure 9). However, in the
multispectral approach the same cultivation (wheat) appears
with different optical characteristics within a distance of a few
km. The anisotropy approach appears to have no problem
depicting the same cultivation with similar optical
characteristics in both areas.
Comparing the multispectral and the anisotropy approaches, the
latter one describes and discriminates more accurately the
boundaries of agricultural landcover types (Figure 10). The
capability of discrimination of crop types is high in both
approaches (see 1 (rye), 2 (winter wheat), 3 (triticale) and 4
(maize) in Figure 10). Different features in fields 5, 6 and 7
demonstrate that each approach displays specific characteristics
of the object of interest, which may be used for further
discrimination.
Fig. 10. Top: „Anisot“ FCC; bottom: „MS“ FCC. Separability
of crops: rye (1), winter wheat (2), triticale (3), plot
with maize seed (4). Plots 5, 6, 7 show different
features in the two images.
Meadows in the wet and marshy area of the Munich gravel
plane at the border to the tertiary hills are partially mowed. In
the MS FCC fresh mowed plots look like bare soil. In the anisot
FCC, the same plots have the signature of sparse vegetation,
describing the real situation much better.
4.2. Classification results
The anisotropy approach showed better results than MSS, as far
as the assignment of the pixels to the available classes is
concerned. The combined approach, however, had the best
overall performance and accuracy.
The anisotropy approach managed to distinguish wheat as one
class in the whole scene with high accuracy results. The other
two approaches failed and classified wheat in two different
classes. Moreover, rye and triticale, a cross-breeding between
wheat and rye, could be differentiated by the anisotropy
approach, while in the two other approaches both rye and
triticale were classified as one class.
The class that represented urban/man-made constructions was
more accurate in the multispectral approach, but often
misinterpreted as coniferous forest in the combined approach.
The latter phenomenon appeared as a buffer zone at the
boundaries of this forest class with other ones. It also appeared
to a high degree in the anisotropy approach, where it could be
noticed in other areas as well. One possible interpretation is that
this phenomenon has to do with the shadow effect of the