Norbert Bolter
Schmittenstr. 29, A-6700 Bludenz, Austria, tel (+49)5552/62291

Brigitte Schosser
Höttingerstr. 36/33, A-6020 Innsbruck, Austria, tel (+49)512/286211

Abstract

The local government of styria collects and analyses zoning plans (land-use plans) of communities. The lecture includes the determination of a norm; based on DXF and E00. A multivariable DXF-checking routine verifies structure and topology. In order to handle the mass of symbols, they have been split into basic elements, which are realised in ‘‘Symbolsets’’. A database describes the connection between basic elements and symbols, which reduce the handling time dramatically. The data is published on the Internet. A static HTML solution is realised; the dynamic version based on ArcView-IMS is made.

INTRODUCTION

Accordingly to the Styrian law (1974) spatial planning is defined as methodical, provident composition of an area, which ensures a lasting, best possible use of an anthroposphere.[1]
An essential instrument of spatial planning is a communal zoning plan, which splits a community into the three main categories building land, traffic areas and agricultural areas. Each of these main categories consist of many proposed land-use - especially building land. Spatial and temporal superimposition’s are possible. Moreover, danger zones, public utilities etc. are shown. Recapitulating we have a very complex map with historically grown plan-symbols. This map is based on cadastral-map, which shows the realty and their owners.
The map is made by specialist engineers or architects and is certified by decision of a municipal council and is controlled by the office of the local government.
The digitalisation of building land from analogue zoning plans is an established project. The data is updated after all changes in zoning plans are made. This extraction has got an important layer. There has been a desire for more information. The extraction building land was not enough.
Digital cadastral maps, which is the basic layer of zoning plans, are given freely to planners (if available). This increase in digital planning, and the planners results are transferred to the office. At the beginning we had poor technical transfer standards, which made data not efficient. We learned that we had to write a voluminous norm including all possible peculiarities.

NORM

The data can be delivered in the structure of Coverages, Shapes or DXF-files. We accept DXF (Drawing Exchange Format), which is a CAD format, because DXF is one of the most popular formats and nearly all products are able to produce and read these files. This exchange format ensures equal opportunity. Architects, who produce these maps mainly work with CAD systems, yet it does not guarantee topological correctness.
Starting to write this norm, there was the big advantage, that a cadalogue of graphical representations existed. It eased the work a lot, yet it did not regarding limitation and possibilities of Arc-Info.
Excluding elements are put in one Layer (Coverage), which insures that these elements do not superimpose. All the other elements are put into separate layers according to their meaning (41 different layers). Not only the layers but also the data content has been defined, which leads to a very voluminous paper .
After the first deliveries we had to notice that some polygons were not closed by a planner. He made lines instead. The holes were made where exact boundaries could not be found. For instance the area’s of overflow are determined within valleys. This valley meets a plane and within this flat area, the planner could not determine the boundaries. The overflow area stops anyway. We had to accept this argument. Such areas can be delivered in line structure too.
DXF-Format was made to transfer drawings. This format does not pay attention to topological relations and a connection between graphic and non graphic is not supported. So we stored non graphic information into Block structure, which consist of text-attributes and their content. Blocks have a location and the superimposition with the graphic-elements formulates the missing connection.
Polygons consist of a closed DXF-Polyline and a Block, which is placed within the polygon (cf. Labelpoints). Arcs are stored as DXF-Polylines also, but the Block is placed within the line, not at the beginning or the end of the line (cf. function near). Points are represented by Blocks. All these regulations and the missing other topological rules have to be regarded by the architect.

CHECK ROUTINE

To fulfil the DXF-Structure may be difficult, if the planner does not have any function on his CAD-Software, which emulate GIS-functionality. So we ordered a check routine, which is made available for free to a planner. This check routine features a big variability, which makes it usable to control all different DXF-Structures (not the elements of drawing). This Software produces a protocol of mistakes, and a DXF-file, which shows the position of mistakes.
The check routine is driven by a ‘‘Rule-file’’, which describes in a symbolic language all necessary examinations. The check routine can be compiled, which fixes all executed examinations and they can not be varied afterwards.

The examinations can be categorised into:

• system-checks
• topological-checks
• attributive-checks.

The system check controls the existence of layers, there contents (entities), Block-definitions, and the contents of Blocks.
Besides the known topological checks (intersections, closed boundaries, neighbourhood etc.) all determinations, which are necessary to assign attributes to geometric elements, are checked. For instance: On a line there has to be one block of a certain name which carries the attributive data.
Missing attributes, wrong attributes and wrong combinations of attributes are shown.

Example:

The software runs within the DOS-SHELL.

All these checks can assure correct data. Nevertheless this data sometimes does not agree to the delivered plot, which is of legal effect. Because we do not have the capacity to compare the data with the delivered plot, we can not guarantee correctness. This is a problem especially within the Internet representation.

SOFTWAREAPPLICTION

The software is compatible with UNIX-workstations and is now reconverted to NT-platform. It splits into:

• data transfer, data preparation, administration (1)
• digital representation (plotting), analysis (2)
• three dimension views (3)
• combination with aero-pictures (4)

ad 1)

DXF-files as well as Shape-files are transformed to covers. Also, if the check routine shows mistakes within the DXF-files, some planners do not repair them. Especially different national language support troubles. So we correct it automatically during the reading of this data. This step includes the inserting of describtive information into the allocated database. Some information is prompted by the operator some information is read from the delivery.

ad 2)

The main problem within this project has been the enormous number of drawing-symbols. Moreover the planner is allowed to invent new symbols, as desired. It would have taken a long time to generate all the shadesets, linesets and markersets, which implicated that this project is to expansive. So the basic elements of drawing-symbols were filtered and realised within the sets. There has been a small number of basic elements. A table describes the connection between drawing-symbol and their basic elements. One drawing-symbol can consist of 3 shade-elements, 3 line elements and one markersymbol. If the system notices a new drawing-symbol, it shows the attributive data. The operator, who is a specialist, in general knows the graphical representation. Otherwise he has to look at the legend of the delivered control plot. The operator prompts the numbers of basic elements. This requires little time and is much quicker then the generation of a whole symbol. Within the plotting routine the area-elements followed by the line elements and the marker are drawn, which needs much processing time. Overall this way is a lot quicker in time of handling.
The building land is extracted. So this data fits into the well established project ‘‘Digitalisation of Building-Land’’. A lot of analyses is done. The comparison with the old data shows the dynamics of this important layer.
Other extraction are not made automatically. Sometimes the polygons of traffic land are transformed into line-structure in order to improve the existing covers.

ad 3)

Three dimensional views of the map are programmed. In this way we hoped to amplify the sensibility of overflow areas etc. This information is used by specialists only, who are qualified to read maps. Moreover, a lot of information is lost in three dimensional views. So it’s use is limited.

ad 4)

The combination of the layer house and the zoning plan, shows the built-up area and the free reserve of building land. Big differences of free reserve of building land between communities effects different prices. People settle just because of price not in there most favoured community. This results in increased traffic.
Often the cadastral map does not include all houses. Ortho-photos made form aeroplanes are superimposed to this map, which helps in this case and in a lot of others. We combined ortho-photos and zoning plan in two different ways. First we coloured the grey pictures. The photo gave the intenseness and the colour comes from the zoning-plan. This combination was poor, even in dark areas just like wood. The symbols could not be distinguished. A combination of the ortho-photo with the boundaries of polygons, and a code describing it, has been successful.

INTERNET

We can observe the trend over the last few years, that GIS is becoming a popular instrument with many people. This is indicated by the platforms ( GIS-Styria, 1988 Minicomputer VAX/ 1992 Unix / 1997 Windows NT) and the costs of storage media (1988 ÖS 150000.-/Gigabyte -> 1997 ÖS 1000.-/Gigabyte).
Ten People worked with GIS in 1990. This number increased to 50 persons (1996) and now some hundred people use GIS by Internet/Intranet. This development can be shown in time of teaching too. (Professional GIS 3-6 months / Desktop GIS 1 week/ Web GIS 5 minutes) [2]
In order to fulfil this necessity, we started early to work at a web solution for digital zoning plans. A static HTML solution was used.
At first you enter a overview of styria, showing a satellite image and the districts of the country. A mouse click within the map brings you to a more detailed picture. In this way the map of a district and the map of commune leads to the zoning plan.
The zoning plan is clipped into rectangles of 625*500 meter according to the cadastral maps. 1300 pixel in abscissa produce a good resolution.
All the necessary HTML-files and JPG-files are made by AMLs (and Alchemy). The operator just has to start this AMLs form his menu and prompt the name of a community. So it is simple to put a new community into the net.
The solution is used by officials of styria but also by officials of the communes. These pages are also frequently entered by dealers of property.
The advantage of this solution can be encountered within the cartographic possibilities. The zoning plan is shown in the customary manner. There are no costs for special Internet software.
The look for simple attributes and a dynamic zoom function is missing.
These restrictions are overcome by ARC-VIEW Map server. Because it is not possible to produce all the symbols within Arc-View just building land in combination with ortho-photos is offered in Intranet.
Now we try to combine the advantages but this has not been completed to date. The images of the static HTML-solution are georeferanced. So it is possible to introduce them to ARC-View Map server, which have the functionality of dynamic zoom. Attributes can be requested and it is possible to find a location for the connected attributes.

[1] Kranjec, H.: Raumordnung in der Steiermark. Skiptum Universität Leoben

[2] Mörth O.: Angewandte Geographische Informationsverarbeitung. Beiträge zum AGIT-Symposium Salzburg 98.