WHAT's THE USE? of a digital cadastral map.

Über die Anwendung von digitalen Katasterkarten.

Comment utiliser un plan cadastral digital?

Jonna Hvidegaard, Ph.D., Head of Department, National Survey and Cadastre (NSC), Denmark.

ABSTRACT:

By the end of 1997 all of Denmark is covered by a digital cadastral map, which will be updated currently as the analogue maps used to be.

The paper gives examples of the use of the map also within areas not directly connected to the registration of real estate. The use of the map by new partners for new purposes is illustrated.

ZUSAMMENFASSUNG:

Seit Ende 1997 ist ganz Dänemark gedeckt durch eine digitale Katasterkarte, die fortlaufend revidiert werden wird wie gewöhnlicherweise die analogen Karten.

Der Artikel gibt Beispiele für die Anwendung der Karte auch für Aufgaben, die nicht direkt mit der Registrierung von Grund und Boden verbunden sind. Die Benutzung der Karte für neue Zwecke wird illustriert.

RESUMÉ:

A la fin de l’année 1997, l’ensemble du Danemark est couvert par un plan cadastral digital, les mises à jour sont faites couremment comme par le passé.

La documentation donne des exemples d’utilisation du plan, et inclue aussi des sujets non directement enregistrées comme bien immobilier. Vous trouverez, aussi, illustrée l’utilisation du plan pour d’autres buts par de nouveaux utilisateurs.

THE CADASTRAL MAP.

Background and status.

The cadastral map of Denmark covers all the country and has been doing so for approx. 200 years.

The present cadastre dates from 1844. The main parts of the maps where measured and constructed earlier as they were originally made in connection with the great land-reform in the last part of the 18th century.

During the years until 1980 – 1985 the single maps were redrawn whenever needed due to wear and tear. The renovation was done simply by copying the old maps. Only in areas with a heavy cadastral activity e.g. around larger cites new cadastral map were made on the basis of new measurements.

Around 1980 the first ideas rose to make a digital cadastral map, but it was not until 1986 the actual project of conversion started. By the end of 1997 the cadastral map of Denmark is in digital form and it is updated currently as the analog map used to be.

The project has been described in several connections already (Hvidegaard and Krüger,1990), (Nielsen and Hvidegaard 1994).

New possibilities for combinations.

The cadastral map has always been a key to information on land. On the map you could see where your parcel was situated, the shape of the parcel and the unique cadastral number. Using the number as an entrance to different registers you could look up the mortgages, deeds, limitations and obligations on that specific parcel.

As both the map and the registers are converted to EDP the information is of course much easier to get at.

Also the combination with other maps rends a whole lot of new possibilities.

To get an idea of the range of possibilities the main registers and maps covering the country are listed below.

DIGITAL TOPOGRAPHIC MAPS.

General topographic maps.

Traditionally the Geodetic Institute now part of NSC has produced the topographic maps of Denmark. The responsibility sill lies on the NSC.

All the topographic maps were published in raster format already 5 years ago. Maps in the scales 1:200.000 and smaller were at the same time made available in vector format. P.t. maps in the scale 1:100.000 is under conversion to vector.

Today a work is going on to produce a map base with an accuracy equivalent to 1:10.000 in order to make that the base for all the map series. The base will be finished covering the whole country in 2002 according to the plans.

Technical maps.

The municipalities have for many years produced maps for administration purposes. Most of these maps are today in digital form. The accuracy of the maps is equivalent to the scale 1:1000 to match the need in build up areas. In rural areas there is not the same need. Some municipalities only map build up areas and others use an accuracy equivalent to the scale 1:2000 or 1:4000 outside these areas.

The utility owners produce other technical maps. These maps are in some cases just covering the narrow line of interest, but in other cases they cover areas of regions and several municipalities.

Ortophoto-map.

A private firm Kampsax-Geoplan has published an Ortophoto-map in color covering the whole country. The photos were taken in the scale 1:25.000 in 1995 The map is available in analog and digital form.

Table 1: Digital topographic maps.

OFFICIAL REGISTERS CONSERNING PROPERTY.

In Denmark quite a few of the official registers are already on EDP. We have

• The Cadastral Register
• The Register of Buildings and Dwellings.
• The Register of Properties
• The Valuation Register
• The Land Register (under conversion)
• The Planning Register

And on top of that we have the Cross Reference Register which combines the main keys from the other registers namely the address, the cadastral number, the property number, the building number and the plan number.

All of these registers cover the whole country and are currently updated.

Main contents and keys of the registers.

The Cadastral Register has been on EDP since 1986, which is 11 years before the cadastral map. The register is maintained centrally by the NSC. The main key is the cadastral number but a couple of years ago also the property number was included. Apart from that the register only contains a few informations mainly about farming and forestry. It is the main entrance to cadastral changes.

The Register of Buildings and Dwellings is kept and maintained by the municipalities. The general rules for the register is set up by the central government, in order to be able to draw information and statistics for the whole country.

This register contains information on the houses such as size, number of rooms, building materials, year of construction etc. It also holds information on the address, the property number and the building number. Further the local municipality may keep information for local use.

The Register of Properties links together the parcels, which together forms a property. It is kept and maintained by the municipalities.

The main key here is the property number, but it also contains the cadastral number and the address.

The Valuation Register holds information on the value of land and buildings. The main purpose of the register is tax.

The Ministry for Taxing is responsible for the register and the tax-department of the local authorities keeps the register updated.

The content of the register is property number, name of owner, value, type of property (parcel, flat etc.) and use.

The Land Register is the register of owners, deeds and mortgage and here you find the legal owner of a parcel. The cadastral number identifies the parcel, and there is a close administrative connection between this register and the cadastral register. The register is held and maintained by the local court, by rules set up by the central government which holds the responsibility, in this case, the Ministry of Justice. The ministry also undertakes the project of converting the register to digital form. The project is still running but is expected to be finished in a few years.

The Planning Register gives access to planning documents concerning physical planning. The register is the responsibility of the Ministry of Housing but the planning departments of the local authorities update it.

The content of the register is plan number, type of plan, limitations in use, max. percentage of building area and height etc.

* Common data operator for the municipalities

** Data firm with state and private shareholders.

Table 2: Digital registers concerning properties.

Table 3: Keys in the registers concerning properties.

EKSAMPELS OF USE OF A DIGITAL CADASTRAL MAP.

Forest declaration

The cadastral map has shown information about forests from the very beginning. Nice little trees are drawn on the old maps and some of the areas are indicated "Fredskov", which in English could be translated "Peace forest". This means restrictions and limitations in use for the owner. The problem is that some of the areas with trees can be "Fredskov" although the word does not appear. To find out whether it is a "Fredskov" or not you will have to make investigations on different maps and in different archives concerning forests. You will also have to look in the Land Register and very often to go out into the field. If it is not made sure that the area is registered the obligations may not be met. New "Fredskov" is still raised especially where the state owns areas but also in return for abolition of farm land.

Fig. 1: Old cadastral map with forest signature.

The responsibility for the forests lies in the Ministry of Environment. Around 1990 the ministry set up a project to go trough the whole country in order to register all "Fredskov".

As the project was running parallel in time to the conversion of the cadastral maps it was not possible to get full advantage. It was agreed however that the forests should be a separate theme in the digital cadastral map and that the Ministry of Environment should maintain the updating.

Having the forests registered on the cadastral map means an official registration, which does not have to be published elsewhere.

Of course the owner has to be involved and notified. In order to find the owner and his address the municipality is involved. From the cadastral map you have the cadastral number and by using the cross-reference register and/or the building and dwelling register the address is found. In the municipality it is possible to find the owner when you have the address.

The project of the forest declaration will be finished in the beginning of 1999.

Protection of near-coast-areas.

In Denmark the coastal area has for many years been protected by a 100-m. zone within which it is not allowed to raise any buildings without special permission.

This zone has recently been extended to 300 m. The 300-m zone is not without exceptions. In cities and town you have houses close to the water and you have harbors. In other areas buildings, summerhouses etc. have been raised between 100 and 300 m. from the coastline. In these cases it is decided that the line shall be close to the buildings already there. But it is also decided that the actual line shall be determined and mapped out in order to clear the situations were there could be reason for doubt. As Denmark has a coastal line of approx. 7000 km. it is quite a job.

The responsibility for nature preservation and in this connection the coastal zone lies on the Ministry of Environment.

The NSC in cooperation with the Ministry of Environment has worked out a possible solution and a prototype using the following guidelines:

First of all the coastal line has to be defined. The Ministry of Environment has found that the ortofoto-map is suitable for that. Here you can se the vegetation, which is an essential factor.

It is easy now to make the computer draw a line 300-m. parallel to the coast.

Houses and buildings on the coastal side of the line appear on the Ortophoto. To se if they are within the old limit a parallel line of 100 m can also be drawn.

A combination between the ortofoto and the digital cadastral map makes a good background for drawing a suggestion for a new protection line.

The suggested line has to be announced to the owners affected by it, and where problems rise a committee will have to go out in the field and settle the matters. In the end the final line will have to be registered.

Having the digital cadastral map available helps to find the owner in the same way, as was the case for the forests.

If the Ministry of Environment chooses so the protection line along the coast can be a theme on, or in close connection to, the digital cadastral map. The updating will still have to be the responsibility of the Ministry of Environment.

Fig. 2: Suggested protection line. To facilitate reproduction selected topographic information here substitutes the ortophoto

Information concerning legal limitations in use of land.

Approx. one year ago a suggestion was put forward in the parliament that a landowner big or small should have information about the obligations and limitations, which were registered on his land and parcels. Of course these registrations are not secret but they are registered in different places on different material and very often they are not easy to get at. Now it was suggested that the information should be directly available to the owner and that the information should be shown on a map.

How big this project will be is difficult to say today. If you include e.g. private easements it can be very large. It could mean a lot of work for the private surveyors among others.

A committee has been formed and as far as I know the main goal so far is to show the official decisions, zones etc. But the committee has not finished its work yet.

As it was a part of the original suggestion in the parliament already that a map should be the background for the information we of course in NSC have made some examples of combinations between maps and registers. The aim is to se how much can be done and to reveal the difficulties. Fortunately the cadastral number is very often included in the registration and that makes it obvious to use the cadastral map.

Fig. 3: Example of a combination between the cadastral map, zones of building restrictions and nature preservation areas.

Using the cadastral map and its connection to the owner will make it possible to drag out the information concerning a specific landowner to present it to him. This presentation again could be in different form. It would be obvious to consider the Internet as one of the solutions.

LESSONS LEARNED AND CONCLUSIONS.

I have chosen 3 cases to illustrate the use of a digital cadastral map. The first one, the forest declaration, is close to the traditional use of the cadastral map. The next two combines the cadastral map with registers and maps in a new way and for a new purpose.

In all 3 cases the solutions are meant to cover the whole country.

The experiences in use are not very extent so far specially on a countrywide base. The cadastral map has been taken into use municipality by municipality from 1989 but the whole country was finished only by the end of 1997.

Smaller tests and jobs have been carried out and we have learned that the interest in using the cadastral map is very large. This also gives a discussion about the price, but that is a different subject.

One challenge in combining registers is that although they have the same key pr. definition the key is not always identical. The registers may have been updated parallel and that always gives problems! After some time the registers diverge. The solution of course is to have an agreement that one part is responsible for the updating. Others can then get the updating from that partner or check his data against the mother-register.

Another problem that occurs in existing registers is that although the key is the same it may not be represented in exactly the same way. There might e.g. be an extra "0" or space somewhere. The problem as such is not so serious, the disagreement can be corrected globally – that is: ones you have found it and if there are not too many!

Combining maps highlights the problem of different accuracies. Lines that should fit, diverge e.g. A god and simple method to illustrate accuracies would be helpful but it is also worth while to find out which line should be shown and which should not. You can easily combine so many information’s that the message is lost.

Certainly you still need the skills of a good cartographer.

REFERENCES

Hvidegaard, J. and Krüger, J., 1990, "Conversion of the Danish Cadastral Maps to digital form", Proceedings FIG XIX Congress, commission 7, page 118-131.

Nielsen, N. and Hvidegaard, J., 1994, "National Cadastral Work in Private Enterprise", Proceedings FIG XX Congress, commission 1, page 102.3/1-102.3/8.

January 1998.