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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol XXXV. Part B2. Istanbul 2004
Input data from
external
and/or partners
producers TOP10DK
Derived databases Products
Figure 1. The TOP10DK database, derived databases corresponding to various degrees of detail and
final output as digital or analogue products
TOPIODK geometry specification. The specification is updated
frequently in order to meet new user requirements.
In general, the geometrical accuracy specification is 1 meter in
all three co-ordinates, but in well-defined object points the
accuracy is significantly better. It is a 3 D (2'4 D) database with
a data model claiming strong requirements on completeness and
on both 2D and 3D topology.
The geometry is based on photogrammetric registration from
1:25.000 scale aerial photos. The revision cycle is laid out to 5
years, i.e. 20% of the country is revised every year.
When the database was established all photo points were
defined a priori in a regular pattern and an aerotriangulation
was measured and computed. The same photo points are aimed
at when the photo flights for revisions are planned for
subsequent years. In this way the photogrammetric models are
located approximately at the same positions and tie points and
geodetic points from the database establishing can be reused.
GPS technology makes it possible to take the photos at the right
position within 50 meters.
Approximately 1.500 photos are taken per year. Since digital
photogrammetry is the dominating production method all
images are scanned. A resolution of 21 ju has proved sufficient
for revision purposes.
External
Data Producers
Aerial Photos
Updates
Semi-Automatic
Database
Es
Process
dein Figure 2. Dataflow for the revision process (after Hoejholt 2004)
Is in the 8
60
Lh
