THE DIGITAL ELEVATION MODEL 1:25.000 (DEM 25) 
FOR THE FEDERAL REPUBLIC OF GERMANY 
Michael HOVENBITZER 
Federal Agency for Cartography and Geodesy, Germany 
Michael.Hovenbitzer@bkg.bund.de 
KEY WORDS: Fusion, DEM/DTM, Multiresolution, Database, Threedimensional, Quality. 
ABSTRACT 
The fusion respectively the homogenisation of the digit 
a nationwide digital elevation model for Germany is describ 
yet existing, digital elevation model with an accuracy of +1 
grid sizes, techniques and dates of data acquisition and, of cot 
from the quality of laser scanning or high resolution photogr 
For checking the quality of each incoming datab 
state are calculated. Regions showing great differences (errors) 
(SAPOS). After checking the data the error-free DTM-Data wi 
be prevented using a distance-dependin 
accuracy. Possible height steps in the data will 
catastrophe of the river „Elbe“ in the year 2002 Germany has 
models with respects to possible flooding areas. Therefore, the DEM25 w 
with an accuracy of 0,5 m and better in these regions. 
KURZFASSUNG 
Die Landesvermessungsámter erstellt gemeinsam mit dem Bundesamt fü 
Jahre 2004 ein die Bundesrepublik abdeckendes, homogenes digitales Gel 
abhängig +1 bis +3 m). Vorhandene Datenbestände der Länder werden 
rscheiden sich hinsichtlich Gitterweite, Erfassungsarten und -zeitpunkt 
50 m) in mittlerer Genauigkeit (d.h. geländetyp 
hierzu genutzt. Die Eingangsdaten der Länder unte 
al terrain models of the federal states (Länder) of Germany to 
ed. The aim is a nationwide, consistent, at the moment not 
to +3 m. The incoming data from the states have different 
ırse, different accuracies. These different accuracies range 
ammetry to the quality of digitalisation of contour lines. 
ase the differences in the overlapping areas adjoining the neighbour 
are checked by field measurements using a DGPS-method 
Il be merged with algorithms that depend on the data 
g adaptation. After the flooding 
an urgent demand for high resolution digital elevation 
ill be supplemented with a high resolution DEM 
r Kartographie und Geodäsie (BKG) bis zum 
ändemodell (DGM, Rasterweite kleiner/gleich 
J igkeiten reichen von der Qualität des Laserscannings oder hochgenauer 
und somit der Genauigkeit jedoch stark. Die Genau! 
Photogrammetrie bis zur Qualität der Digital 
modelle der Überlappungszonen der Eingangsdaten ber 
sungen mittels DGPS (SAPOS) geprüft. Nach der Qualit 
Mögliche Höhenstufen werden durch eine distanzabhängige Anpassung 
h hochgenauen digitalen Geländemodellen in Deutschland. Aus 
„Elbe“ im Jahre 2002 besteht eine erhöhte Nachfrage nac 
diesem Grund wird das flächendeckende DGM25 durch hochgenaue DGMe (Genaui 
tungsgefährdeten Gebieten ergänzt werden. 
1 INTRODUCTION 
At the moment there is an urgent need for digital terrain 
models and, respectively, digital elevation models. One re- 
ason for this demand is, for example, the flooding catastro- 
phe of the river „Elbe“ and its tributaries that occurred in 
August 2002. For calculating flooding predictions a precise 
DEM is needed. The growing market of mobile telephone 
systems is another reason. The mobile telephone compa- 
nies are using elevation models for planning the best loca- 
tions for their aerial masts. 
The Federal Agency for Cartography and Geodesy (Bun- 
desamt für Kartographie und Geodäsie = BKG) of Germa- 
ny offers three nationwide digital elevation models for the 
mapping scales 1:50.000 to 1:1.000.000 with a minor ac- 
curacy of about +20 m. Further, the federal states (Lánder) 
Germany have digital elevation models for the mapping 
of 
-5.000 to 1:50.000 for their areas with an accuracy 
scales 1 
isierung von Hóhenlinien. Zur Qualitätsuntersuchung werden Differenzen- 
echnet. Regionen mit großen Differenzen werden durch Feldmes- 
ätskontrolle werden die Daten genauigkeitsabhängig fusioniert. 
angeglichen. Aufgrund der Flutkatastrophe der 
gkeit 0,5 m und besser) in überflu- 
of +0.3 to +5 m. But presently there is no nationwide ele- 
vation dataset, which fulfils the needs of many customers 
of BKG. For this reason a new digital elevation model is 
just being calculated. The DEM is built up for the mapping 
scale 1:25.000 and will have an accuracy of £1 to +3 m. 
2 DECISION OF THE ADV 
The Working Committee of the Surveying Authorities of 
the States of the Federal Republic of Germany (Arbeitsge- 
meinschaft der Vermessungsverwaltungen = AdV) decided 
in Mai 2003 that the states shall build up a new digital ele- 
vation model of Germany (Decision | 12/12). According to 
this resolution the BKG is responsible for the homogeni- 
sation and the fusion of the datasets of the states. The first 
release of the elevation model was terminated for the year 
2004. Furthermore, the accuracy of the model was speci- 
fied with +1 to +3 m. The accuracy depends on the terrain 
type. In plain areas the accuracy has to be 1 m and in moun- 
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