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locations near urban environments. On this
data set unsupervised classification is applied.
This method results in ten spectrally different
classes i.e. classes are scaled according to
the level of emitting thermal energy. After that
information category of the particular class is
defined, and classes with stronger thermal
radiation are separated (shown in different
shades of yellow, Figure 1).
These information about thermal radiation are
used as a basis for the next set of data. The
purpose of the new data set is a more precise
definition of the area of interest. This second
type of data for classification uses TM bands
5,7 and previous band combination. We used
this band combination because the warm
objects have emission peaks that fall between
0.5um and 9.5um and thus can be detected in
MidInfrared TM Bands 5 and 7. Bands 5 and 7
are useful for pinpointing small, warm targets
because of their greater spatial resolution.
Thermal infrared Band 6 is designed to
measure surface temperatures. The unsuper-
vised classification is used for this data
combination (Figure 2). The shade of the
yellow colour represents the warmer surfaces.
Results given by the method are checked on
the map. It is obvious that urban areas are
specific for their increased thermal emitting.
Comparing with map 1:25000 it is easy to
eliminate classes related with urban objects
and areas. The rest of the locations compared
with the SPOT (p) images gives with large
probability possible locations of garbage repo-
sitory.
The same method is applied on the variety of
areas near urban regions for, which it is logical
to assume that they are garbage repositories.
The results were validated on the field.
Polygons of the different garbage repositories
define the minimal area cca 12000 m^ for
which this method is still valid. So the method
is correct for discovering larger “wild”
repositories and for the controlling of the
known repositories growth based on the
satellite images taken in various times (Figure
3).
DATABASE DESIGN
Project database was developed with
ARC/INFO (rev. 6.1.1). Graphical data is
modelled with line features and stored inside
ARC/INFO line coverage. Attribute data
describing garbage repositories is stored
within two tables. One of them is arc attribute
table (AAT) of the line coverage, and the other
is standalone table called GARBAGE_T.
Figures 5 and 6 show these tables with
names, types and descriptions of the fields.
This database design enables the user to track
and store information about garbage
repository changes during the time. First table
(AAT) keeps data about each measurement of
the garbage repository. GARBAGE_T table, on
the other hand, keeps data that is time
irrelevant and same for every measurement
performed (i.e. commonly used name for the
garbage repository or its geographic location)
for each garbage repository. Each
measurement (for all garbage repositories
examined) has its own row in the coverage
AAT table. Rows in AAT table that have the
same value for the "cov-id" field represent the
same garbage repository. Row representing
the last measurement for one garbage
repository has the value of the “validity” field
set to *T" (true), and all other rows for that
repository has this field value set to "F" (false).
GARBAGE T table contains one record for
each garbage repository examined. These two
tables are related to each other with the field
“cov-id”.
The reason why the graphical data is modelled
with lines and not with polygons is because
this revision of ARC/INFO (rev. 6.1.1.) doesn't
have support for overlapping polygons, but
perimeters and areas data of garbage
repositories are still required. Because of that
some small programming was done to
perform digitalisation of tracked garbage
repositories as polygons (in the separate
temporary coverage), and after the necessary
calculation, data is imported as lines in the
main coverage.
Capabilities of such designed GIS database
besides digitising and storing new information
of garbage repositories include search and
display of data and measurement of garbage
repository changes in the course of time. By
that measurement the user can estimate
growth of the garbage repository and its
status, whether it is in every day use (active)
or not (abandoned).
CONCLUSION
The experimental method is defined as a
reliable way to detect garbage repositories on
the available satellite images (Landsat TM and
SPOT panchromatic). Also, a database design
adequate for tracking of the garbage repository
changes in the course of time is suggested.
The method can as well be applied to detect
wide uncontrolled repository in order to
supervise the environmental polluting. Of
course, analysis of the different satellite
images with better resolution and radar
images can ensure information of the other
garbage repository caracteristics, and enlarge
probability of smaller garbage repository
detection.
Intemational Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998
237