is that street names connected to the centre lines of roads and
house numbers are part of the mapping and open up for con-
nection to existing administrative databases.
The map in 1:200 000 which covers Denmark in 4 sheets has
been converted to digital form. The next edition will be
updated purely digitally. The road centre lines of this map are
at the moment being transformed into a road database by estab-
lishing connections between the centre lines and all town
names, CIP codes and information from the Danish Road
Administration.
Greenland
All mapping activities in Greenland have been suspended due
to lack of resources. Looking at the Northern Greenland Map-
ping Project, all data capture is finished, and 34 sheets are
published.
The Faroe Islands
The mapping project of the Faroe Islands is continued and at
the moment 23 sheets have been plotted and 16 sheets have
been published.
The future
At present a lot of test exercises are taking place in order to
establish cooperation between the National Survey and local
communities which are responsible for the large-scale technical
mapping of Denmark. The idea is that the National Survey
shall utilize information from the local communities in order to
minimize productions costs.
Lars Tyge Jorgensen
THE CADASTRE
Introduction
Registration of land, titles,interests,mortgages,easements, etc.
is divided between the National Survey and Cadastre and the
offices of the Land Registry.
In accordance with the Development Act, all alterations of
boundaries are to be registered in the Cadastre. Alterations are
registered on the basis of documents worked out by licensed
land surveyors in private practice who also do the surveying
required. In the National Survey and Cadastre the areas, etc.
are entered in the register, and the new boundaries are drawn
on the cadastral maps. When alterations of property have been
registered, the keeper of the Land Registry and the tax assess-
ment authorities are notified.
The cadastral register has been on edp for six years.
A conversion of the maps to digital form is going on. 10-15
per cent is on a digital form today.
Cadastral maps
In Denmark the entire country is covered by cadastral maps.
The maps have been kept up-to-data with registered alterations
of property since the start of the Cadastre in 1844. The scale
of the maps is 1:4000 or larger.
The majority of the maps are "island maps", i.e. every village
is on a separate map. The maps were originally measured by
plane table survey, and they have all been redrawn one or more
times. The towns were registered for cadastral purposes for the
first time 1865-1875. The maps are in scale 1:800 and are ba-
sed on traverse survey.
73
Since the turn of the century new plans have been produced on
the basis of terrestrial surveys and since 1960 on the basis of
photogrammetric surveys. Surveys carried out after 1934 are
normally linked to the Danish national grid.
The cadastral maps are mainly intended for the public registra-
tion of land, but they are also used for administrative purposes,
planning, etc. by authorities, public institutions and by private
persons.
Reference network
Control points for cadastral measurements have been coordina-
ted using bundle adjustment with added parameters.
The result of the coordination is a densification of the existing
2 km net of triangulated points down to a density of approx.
400 m. The photo scale is preferably 1:8000 - 1:10000 and the
overlap 60/30.
The accuracy is tested in the field by measuring distances
between coordinated points using edm. The standard error on
a photogrammetrically coordinated point is less than 5 cm.
In connection with the conversion of the maps to digital form
it was agreed that an accuracy of 10 cm on the control points
was sufficient for that purpose. This was obtained using a
photo scale of 1:18 000.
An edp-based register of the coordinates for control points -
about 360 000 points - has been established. The observations
are being converted in connection with the conversion of the
cadastral maps.
Present activities
A conversion of the cadastral maps to digital form is going on.
The conversion is not just a matter of digitizing the existing
maps.
The "island maps" were not measured on a common reference
system. In order to relate the contents of the maps to the
reference system of today, you have to partly reconstruct the
maps. Information from the field, in the form of orthophotos or
photogrammetrically produced line maps, and existing mea-
surements from the updating procedure are used in this connec-
tion.
The accuracy of the new map depends very much on the accu-
racy of the control points and the amount of measurements
used.
As the accuracy is also expensive, you will have to watch out
for a balance.
Today we have given up the aerotriangulations for the renova-
tion of the control points. We have found that a recalculation
of the points from the existing observations, supplemented with
a few new, will give us an accuracy sufficient for this purpose.
We also use less measurements and more digitizing of the old
maps today than we intended when we started in 1986.
These changes mean that covering the whole country with di-
gital cadastral maps is today calculated to cost less than half
the price that we anticipated 6 years ago.
The conversion is partly financed by user-payment.Therefore
the speed of the conversion is very much depending on user
HO Oy < Bod
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