19.
1o
sts of
sts of
Ires à
| data
o the
ptimal
sition
indsat
main
tep in
ta set
(scene KJ 62/245 from 22.08.1995) was used which had been
previously rectified on a topographic map (scale 1:25000). The
average rms error was about 0,5 pixel. According to the spatial
resolution of the Landsat- TM data the resampling size was set
to 30 x 30 m2 The next step in processing the data was the
radiometric correction of the data which is precondition for any
quantitative comparisons of vegetation state analyses. It was
applied the atmosperic correction software ATCOR for
ERDAS-IMAGINE 8.2 (Richter 1990). Some empirical tests
with the knowledge of the real vegetation types of the study
area have shown good results in using the calibration model of
Bolle which obtained high differences in the vital green
vegetation canopy. For a successful application every data set
was calibrated with the same reference arcas of dark pine
forest consisting of trees aged between 70 and 110 years, and
situated beyond the mining compact line. The visibility used
for the atmospheric correction of any data set is documented in
table 1.
2.2 Vegetation index NDVI and their GIS integration
The vegetation assessment was carried out with the parameter
NDVI (Normalised Difference Vegetation Index). Since
Kriegler et al. (1969) it is not only the most well-known
parameter featuring the vegetation cover: own investigations
with other parameters like the MSAVI2 (Qi et al. 1994) or the
curvature value VM2 (Weichelt & Herr 1987) did not lead to
better results as compared to the NDVI utilisation.
Only those habitat types are integrated in the environmental
long-term monitoring which have relatively stable species
composition for a long time, i.e. where human impact is
relatively weak. As suitable for the monitoring 15 out of the 28
mapped habitat types were selected. They were classified into
two categories: (1) Forest habitat types with typical tree
vegetation and (2) Pioneer forest and heath habitat types with
typical poorly sparsed vegetation cover. As the NDVI values
were determined by habitat type scaling was carried out in
relation to the habitat types. Figure 3 shows the eight
respectively seven NDVI levels of both categories with detailed
information in the upper level or in the lower level.
Considering remotely sensed data from Landsat-TM which are
suitable for average scales, only those habitats were analysed
with NDVI values that have an area dimension of more than
one hectare. These requirements were considered in creating
the GIS. The habitats selected per type and dimension were
masked out (Fig. 3 and Fig. 5), the NDVI calculated in them
and the vectorised results transferred into the GIS.
The technological chain from the georeferenced radiance image
as input to the output vector data representing the vitality state
of the habitats. The transformation of the results into vector
data was a necessary step to meet a central requirement of the
customer's GIS software.
Habitat related vegetation state
NDVI levels
1 2
-1-0.5 0.5-0.58 0.58-0.630.63-0.68 0.68-0.73 0.73-0.78 0.78-0.83 0.83-1
1 2 3 4 5 6 7
EN C7 ESS
-1-0.1 0.1-0.2 0203 0304 0405 05-058 058-1
Long term monitoring habitat types
Forest habitat types
[-] EH
1 2 3 5 6 7 8 9 27 28
Pioneer forest and heath habitat types
[1 E33 E EZ
4 10 18 19 22
Fig. 3: NDVI scaling in relation to monitoring habitats
Intemational Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998 153