airphotos in the scale 1: 5 000. The average size of the 
area pertaining these individual buildings was 0.125 ha. In 
densely built-up areas these buffers merged into bigger 
polygons. The contours of individual buffers dissolved in 
that process and uniform areas of these polygons were 
taken into account for further elaboration (Fig. 1). 
The centroids of houses from June 1993 were buffered 
and the same procedure was repeated with the centroids 
of houses from June 1997. The built-up areas for these 
two years were obtained separately. Overlaying the layers 
with buffered centroids, the locations of pulled-down 
houses were identified. Next, the buffers that were 
common for both layers were removed. The remaining 
presents the augmented built-up areas in Slovenia in the 
period from June 1993 to June 1997. 
Figure 1: Schematic presentation of buffered centroids. 
- black buffered centroids: state '93 
- gray buffered centroids: new built-up 
from '93 to '97 
The calculation of the augmented built-up areas by first 
subtracting centroids and buffering the remaining would 
be a much faster method but would not enable the 
merging of adjacent buffers, thus leading to an 
overestimation of the augmented built-up areas. In our 
case the calculated augment of built-up area would be 
greater by 41.5%. 
3. ESTIMATION OF LAND COVER CHANGES DUE TO 
AUGMENTED BUILT-UP AREAS 
The data layer of augmented built-up areas was overlaid 
onto the compiled Statistical Land Cover/Land Use GIS of 
Slovenia-state '93. The areas of wooded and agricultural 
land cover categories that turned into built-up areas have 
been determined (Fig. 2). When the new built-up areas 
were detected within existing built-up areas, they were not 
considered as land cover/use changes since these buffers 
did not change the cover/use categories. The buffered 
centroids that were located with more than 50% of their 
areas over water, railways or roads were considered as 
mistakes and removed from the data-layer. 
In the final stage the layer of augmented built-up areas 
was merged with the layer of administrative boundaries 
and thus the augmented built-up areas for each statistical 
region and for the whole Slovenia were obtained (Tab.1). 
In Slovenia in the period from June 1993 to June 1997 
most augmented built-up areas have expanded on 
account of agricultural areas (Fig.3). The statistical 
regions number 6. and 9. have the highest change of 
agricultural land cover to built-up. 
Legend: 
A = agricultural area 
F = wooded area 
W = water 
B = buffered centroids: 
black = state '93 
gray = new built-up from '93 to '97 
Figure 2: Schematic presentation of new built-up areas 
overlaid onto the Land Cover/Land Use GIS of Slovenia - 
state '93. 
But it is the graphical presentation of this data that gives 
us the essential information, i.e. the geographical 
distribution of the phenomena. As expected, the built-up 
areas increased mostly around urban centres. However, 
an exception is the area of Savinja valley where the 
augmented built-up areas are nearly evenly distributed 
over the whole valley, which is categoriesed as I st quality 
agriculture land. The geographic distribution of the 
augmented built-up areas, using a relatively simple and 
time efficient method, renders new qualitative information, 
which would never be revealed by presenting these data 
only in the classical tabulated form. 
4. CONCLUSIONS 
The Statistical Land Cover/Land Use GIS of Slovenia is 
the first numerical GIS of Slovenia that comprises a 
uniform thematic layer of the whole territory. The 
Statistical Land Cover/Land Use GIS of Slovenia - state 
'93 officialy confirmed that much more area of Slovenia is 
under forest than it has been officialy reported. The 
improved resolution of satellite scanned data used in the 
Statistical Land Cover/Land Use GIS of Slovenia-state '97 
will enable a better delineation of land cover categories 
down to 15 hectares of minimum mapping unit. Since the 
geographical heterogenity as well as the small field sizes 
are the characteristics of Slovenia, this improvement is an 
important contribution to a more operational use of the 
compiled Statistical Land Cover/Land Use GIS of 
Slovenia. 
The Statistical Land Cover/Land Use GIS of Slovenia- 
state '97 will enable us to estimate the land cover/use 
change in the period from 1997 to 2001 due to augmented 
built-up areas more accurate. In addition, the three level 
of roads will be included as well as the built-up areas of 
larger industrial objects, warehouses, parking places, etc., 
which exceed the size of 20 m buffered centroids.