GEOSTAT the Service for Spatial Data in the Swiss Federal Administration
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GEOSTAT The service for Spatial Data in the Swiss Federal Administration Office fédéral de la statistique Bundesamt für Statistik Ufficio federale di statistica Swiss Federal Statistical Office Neuchâtel, 1999 OFS BFS UST Introduction: Spatially related statistical data In connection with n 1990 the population of Switzerland totalled First steps towards an accurate spatial the many new tasks I6.9 million people. Settlement and urban areas reference of statistical data and problems con- covered an area of 242,000 hectares, with an fronting us today, additional 100,000 hectares of legal construc- A decisive step towards a more precise spatial there is a growing tion zones still undeveloped. Well over 25 % of reference was taken at the end of the sixties by need for evaluating the country is afforested and another quarter re- the Institute for Local, Regional and National regional data inde- mains unproductive in the form of rocky terrain, Planning (ORL) at the Federal Institute of Techno- pendently of admin- brush and scrub, glaciers and lakes. logy, Zurich. The ORL scientists developed a na- istrative bodies such tional planning system known as «Informa- as local communi- These figures are arbitrarily selected from the tionsraster». In addition to local community data, ties. With the advent wealth of data largely provided by the Swiss Fe- this system included a survey database built on of geographic infor- deral Statistical Office. Much of this data, which a grid network of spatial unit areas of 100 x 100 mation systems, the is available both for professional purposes and m (1 hectare). The land use information estab- compilation and dis- to the public, is informative on its own. Other fig- lished in 1972 and based on the 1:25,000 na- tribution of digital ures provide relative information in combination tional topographic maps proved to be the most data based on small, with selected data. Particularly interesting in a important data set within this hectare database. flexible unit areas is country as widely varied as Switzerland is the Each hectare was coded according to the pre- gaining ground. possibility of combining statistical and survey dominant type of land utilization that could be data such as topography. Until only a few years identified on these maps. This brochure gives ago, the smallest unit available for regional sur- concise information veys was the local community. The resultant The national planning database concept was on the services and data on population density – for example in designed for continuous updating with important possibilities of the thickly wooded and mountainous communities – regional planning data giving information on resi- spatial database of was of little value since the populated areas in dential and working populations, economy, build- GEOSTAT operated such communities are only a small percentage ings, education and training, culture and recrea- by the Swiss Federal of the reference area. tion, health and social security, traffic, supply Statistical Office. systems and the state of local planning. The ef- Structure and opera- forts and resources required for the collection, tion of GEOSTAT are storage and processing of all this data on a hec- summarized and in- tare grid basis were underestimated in 1970, formation on the ge- however. ometry and the con- tents of its data sets This kind of system is known today as a «geo- is given. graphic information system». Thanks to the Examples of applica- enormous progress in microelectronics, such tions show how systems now have a capacity far beyond the GEOSTAT can be dreams of their originators twenty years ago. used for solving sci- entific and practice- related problems alike, e.g. in the fields of regional planning and envi- ronmental research. Thematic map based on GEOSTAT data 2 What is a geographic information system ? their specific characteristics (attributes). Spatial relationships (topology) between the objects and their surroundings are also defined. Land use Objects are the smallest elements within a GIS which can be associated with a spatial position Demography: and with attributes. Population per ha • Geometrical data define the absolute and rela- tive positions of objects, based on their coor- dinates within a standardized coordinate sys- Geotechnical tem (GEOSTAT uses the Swiss national coordi- map nates defined by the Federal Office of Topo- graphy). Administrative • Attribute data describe the thematic, non-geo- boundaries metrical characteristics of objects. Attribute data are stored separately and linked with the geometrical data by a coding system. Real world Geographic information system he purpose of a geographic information Selection and combination of different data Tsystem (GIS) is to represent the real world in 29 the form of a data model. By transforming and The efficiency and capacity of a geographic in- 441048 processing simulated data in such a model formation system depend on its capability of world, processes affecting the environment can systematically linking various data and deriving be investigated. The results can be a basis for and displaying results from such combinations 612 administrative, economic and scientific deci- as clearly as possible. sions. 5191175 A typical example of a data intersection is the 49916 The spatial data in a geographic information sys- noise emission investigation in the lower Valais, tem covers on one hand: Switzerland, shown on page 14. In order to find 55 5<432 • the atmosphere out how many local inhabitants would be affect- 10 24 8 • the surface of the earth ed specifically by railway noise, GEOSTAT com- • the soil pared computed noise emission ranges with 13 5 7 13 6 and on the other: data taken from the national census of 1990. 4452418 • population and economy The geometrical allocation of population data • technical and administrative installations such was based on digitized coordinates for all resi- 712930 as buildings, industrial plants, infrastructure, dential buildings registered by the census. etc. 4 7 17 <4 • other economical and ecological aspects. Finer differentiation is easily possible with GEO- 65 STAT if the necessary attribute data is available, The data contained in geographic information such as selected age groups, professions, etc. systems can be systematically registered and processed based on a uniform spatial reference system. Real objects are modelled in a GIS by defining their spatial position (geometry) and 3 Types of data geometries Accuracy and representation possibilities of point samples Point data, defined by XY coordinate pairs, Points regularly arranged in a lattice can also be such as the centre of a building or a district. represented as a grid. A good example is the Swiss land use statistics 1979/85 which is based on point samples located at grid intersec- tions. Information on the actual type of land use Point data in an equally spaced grid are also is identified and stored for each point. Each referred to as a dot matrix or a lattice, e.g. sample point thus classified with an attribute sta- the official Swiss land use statistics. tistically represents the area of one grid cell, in this case one hectare. In case of grid or raster data, attributes are The error involved in this kind of point sample allocated to the cells of a uniform grid, e.g. data depends on the number of points for each population per hectare. attribute within a given evaluation area, as well as on the distribution of these points. Small or linear objects (such as buildings and roads) are Line data are defined by the XY coordinates of their represented only in an incomplete and inconsist- origins and ends (nodes) and of intermediate points ent way, while large, contiguous areas of land (vertices); for example river or road networks. use (such as forests or arable land) are repre- sented with greater precision. This must be taken into account for data analysis and inter- Polygon data are defined by the XY coordina- pretation. tes of their boundary lines; e.g. lakes, legally protected areas. Reproduced with the permission of the Federal Office of Topography from 09.11.1994 Swiss land use statistics 1979/85: the two illustrations show the same region – on the left as an aerial photograph showing superimposed locations of the point samples, on the right a raster image with color-coded types oft land utilization. 4 Tasks and operating mode of GEOSTAT From a planning database to GEOSTAT Datenherr GEOSTAT Benützer Geokodierte Daten Bearbeiten von Anfragen n 1976 the national planning database was Anfragen Itransferred from the Institute for Local, Re- Beraten der Benützer gional and National Planning (ORL) to the Swiss und der Datenherren Resultate Federal Statistical Office. This changed the for- merly task-specific concept of the database to Aufbau und Unterhalt an open system, whose spatial data were, stage der Datenbank by stage, expanded. In connection with the Swiss land use statistics GIS 1979/85, the integration of a modern geogra- Datenbank phic information system to replace the existing «Informationsraster» and to provide the data pro- cessing infrastructure for the new land use sta- tistics was evaluated. In 1987 the decision was taken to procure such a system and to set up a specialized unit at the Federal Statistical Office – the GEOSTAT user service – to manage the new GEOSTAT services system and above all to councel the data users. Since then there has been a vast growth in the amount of data and in the requested evaluations, analyses and digital products . GEOSTAT has now matured into an operational system and the integration, utilization and dissemination of service facility held in high esteem by numerous their data. Data is released to GEOSTAT by the specialists. specialists concerned, who are responsible for its accuracy, validity, definition and updating and who decide on the specific conditions or even- Organization and operation of GEOSTAT tual restrictions for the utilization of their data.