International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV ‚ Part B4. Istanbul 2004
tain areas a lower accuracy of 3 m is allowed. Generally the
grid width of the model is set to 50 m.
The AdV specified that the states will deliver their datasets £
to the BKG. The fusion and homogenisation have to be
calculated by the BKG.
3 DTM/DEM DATABASES OF GERMANY
In Germany the responsibility for surveying is regulated by
law. The states, for example Bavaria, are concerned with
the map scales 1:500 to 1:50.000 for their respective are-
as. The BKG is responsible for the map scales 1:100.000
y to to 1:1.000.000 for the whole of Germany. In the field of
not DEM/DTM production there was an analogue border of
rent responsibility. Many states now have a DEM or DTM with
ange a good accuracy and resolution. An overview of the DEMs
ines. or DTMs of the states and the BKG is given below.
bour
thod 3.1 DEM DATABASES OFFERED BY BKG
data |
ding | In table 1 the DEMs offered by the BKG as nationwide
ition | datasets are described. Because of the low accuracy and the
)EM fact that there is no updating, the demands for the datasets
decrease. 3 DEMO :
DEM2S (_bkg
DEMI000 | DEM250 DEM50 b
Scale 1:1.000.000 1:250.000 1:50.000
pi Grid width 30x50 200x200m 1x1” Figure 1: DEMs offered by the states
Accuracy 2 +20 m +20 m
leich
den Planned no no no
Junt Updates el ER 4.1 FUSION
lade Method Digitalisa- Resampling Digitalisa-
nn of data tion of of DEM50 tion of The datasets of the states were delivered to the BKG in
et acquisition | contour lines contour lines the years 2002 and 2003. The first task was the inspection
niert. Table 1: DEM-Datasets offered by BKG of completeness of the datasets. The data should cover the
e der whole area of each state, but often the states had collected
AUS height information beyond their boundaries. The next step
rile 3.2 DTM DATABASES OFFERED BY THE STATES was the transformation of the coordinates into a uniform
coordinate projection and height system. Then the calcula-
Figure 1 depicts the best available DEM/DTM data from tion of differences at the overlapping boundary areas was
e ele the states in the year 2001 (AdV, 2001). The states in the done. This is the main part of the fusion Work, because
ymers western part of Germany offer mostly DEMS quality, which these areas are covered by two or sometimes three data-
del is has an accuracy of about 40,5 m. In the eastern partofGer- ^ sets. Because of different data acquisition methods and for
pping many there is mainly DEM25 quality available, which is other reasons differences have to be expected. The methods
3 Til. precise to about +2 m. In some states, for example Baden- ^ of data acquisition are mainly :
Württemberg, the surveying authorities have planned or
executed projects for building up a high resolution DEM L E
for special regions or the whole state. e 5 orc! Scanning
a Photogrammetry (for example profiling or measuring
itsge- 4 TASKS OF BKG contour lines)
cided e Digitalisation of analogue map contour lines
al ele- The main part of the work for building up the DEM25 for
ling to Germany is the fusion of the datasets of the states. The
ogeni- datasets have mostly an overlapping zone at the boundary ~~ The datasets will be merged after inspecting and elimi-
1e first between two states. The homogenisation is another work- nating the -differences. Therefore, the datasets should be
e year intensive item for the BKG. calculated depending on the input data accuracy. Possible
speci- Furthermore, the quality control of the datasets of the states height steps in the data will be prevented using a distance-
terrain and the final DEM are important points for building up the depending adaptation. Another point of the work will be
moun- DEM25. the homogenisation of the datasets. The final dataset will
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