Spatial data are digital information, which on the surface a certain spatial location can be assigned ( Geoinformation, georeference ). You can be directly obtained primary data or further processed secondary data. Of particular importance for spatial data are metadata that describe the actual spatial data for example with respect to a time reference or origin. Spatial data are divided into spatial reference producing spatial data ( in Germany as " basic spatial data ", in Switzerland called " georeference "), which (in Switzerland, by the competent authorities of the cadastral survey ) is usually provided by the Surveying Authorities of the States or communities be and geodata derived from different spatial specialist databases. You will be guided in a geographic information system that can be accessed through an geobrowser in Internet-based systems.
A common object modeling in geographic information systems (GIS ) is such objects on the one hand with its geometric form (shape ), on the other hand store (attributes ) with the associated property information. The latter may also refer to a reference to the geometric object. Theoretically there is no limit in the dimension of the geometric shape. And the time is often used as a dimension, such as measurements of various remote sensing data or time points.
- 2.1 Completeness of
- 2.2 Logical Consistency
- 2.3 Position accuracy
- 2.4 Temporal accuracy
- 2.5 Thematic accuracy
- 6.1 Examples of spatial data
- 6.2 More
- 7.1 Free geodata
- 7.2 Legal framework of spatial data
Modeling of spatial data
In general, the geometric shape primitives point, line and area can be distinguished. Surfaces are often simply modeled as a polygon. In demanding applications, this is not enough; also curvilinear surface boundaries are necessary and surfaces with holes ( enclaves ) as well as areas with spatially separated parts ( enclaves ) may occur. Since the late 20th century, the aim is to model spatial data in accordance with international norms and standards. In the standard factory ISO 191xx which there is the International Organization for Standardization standard ISO 19107 Geographic information - Spatial schema that normalizes exactly this area.
Even if the objects have only two-dimensional shapes, they can be embedded in the three-dimensional or two-dimensional space. That is, for example, a point that three coordinates (x, y, z) and two coordinates ( x, y) will be saved.
In addition to the geometry (shape, size and location ) of the objects the topological relationships of the objects to be modeled. Serve this purpose, the basic topological forms node, edge and stitch. In simple systems, the points correspond to the nodes, the lines of the edges and the faces of the mesh. On the explicit modeling of the topology can be omitted, if it can be derived from the geometric data. This is the case of simple systems, the case when the three-dimensional geometric data is available. Two-dimensional geometries are not sufficient as a rule to derive a topology; However, an equal height and a height- separated crossing ( bridge ) for example, are topologically different, in the two-dimensional geometry voneinenander not distinguishable.
Quality of spatial data
The quality of data can only be assessed on the basis of quality characteristics in terms of a concrete question. As data quality, the amount of data characteristics are known, enabling the use of data for a specific task. These data characteristics should be documented in the appropriate metadata. The quality parameters of the ISO standard ISO 19113 are:
(complete ness ): presence or absence of objects, their attributes and relationships
- Data income ( commission ): Record has additional information
- Lack of data ( omission ): Record contains less data than specified
(logical consistency ): adherence to logical rules of the conceptual, logical and physical data structure
- Conceptual consistency ( conceptual consistency ): Compliance with the conceptual schema, eg for upgrades
- Consistency values (domain consistency ): Compliance with the range of values, for example, no negative values in a population mapping
- Format consistency ( consistency format ): Comparison of the data set with the physical data structure
- Topological consistency ( topological consistency ): accuracy of encoded topological characteristics, such as Neighborhood relations must be maintained
- Geometric consistency ( geometrical consistency ): To what extent does the spatial data set with the geometric conditions of the associated specification match, eg no duplicate digitization points
( positional accuracy ): Accuracy of the position of objects
- Absolute ( external ) accuracy ( absolute or external accuracy ): conformity to established coordinate values with true coordinate values
- Relative (internal ) accuracy (relative or internal accuracy ): correspondence relative positions of objects to each other with true relative positions
- Raster data accuracy ( gridded data position accuracy ): Consistency of raster data position values with true values
(temporal accuracy ): accuracy of time information and the temporal relationships of objects
- Accuracy of time measurements ( accuracy of a time measurement): Information about a record on the accuracy of the indication of time, eg the minute, daily basis
- Temporal consistency (temporal consistency ): accuracy of temporal events and sequences, eg Order of land use
- Temporal validity (temporal validity ): To what extent does the data set with respect to the required time, eg Time indication of the type: year-month- day
( thematic accuracy ): accuracy of quantitative attributes and of non- quantitative attributes - assignment of objects to object classes and correctness of the relations
- Accuracy of classification ( classification correctness ): Voices objects or their attributes with the assigned classes coincide, eg Assignment to the river, instead of path
- Accuracy not quantitative attributes (non- quantitative attribute correctness ): eg Of use of land
- Accuracy of quantitative attributes (quantitative attribute correctness ): eg Area of land
Legal framework for spatial data
→ Main article: Rights of geoinformation
If and when free or for government agencies in the public domain spatial data may conflict with the protection of personal data in Germany is still largely unclear. Initial efforts to shed light on the topic of spatial data and data intensive, were made by the Commission for geoinformation industry. These and the Federal Ministry for Economic Studies gave to the Independent Centre for Privacy Protection Schleswig -Holstein in order. The latter came to the study published in September 2008 to the conclusion that at present can be brought both the interests of the interested in using points, as well as the data protection concerns with the existing statutory rules inadequately in compensation. In particular, the initiated also at the EU level, the INSPIRE process requires a modern spatial information law, which even with the geodata access laws of the federal and state governments (for example, which came on 1 August 2008 in Bavaria in force Spatial Data Infrastructure Act) is not created. These laws fall back on rather hergebrachte access arrangements and do not respond to the new challenges for use of spatial data and the protection of privacy rights of individuals.
Since spatial data can also affect national security interests, such legislation restrictions of freedom of access are planned so far.
In 2009 Germany joined the Spatial Data access (Law on access to digital spatial data - GeoZG ) came into force. The law aims to build a national spatial data infrastructure. It provides the legal framework for access to spatial data, spatial data services and metadata of geodata-holding bodies ( " geodata holding bodies of the Federation and the Federal immediate legal persons governed by public law ") and the use of these data and services, particularly for actions that impact on the environment may have. Since 2012, the federal spatial data free of charge. The announced on March 22, 2013 Regulation ( GeoNutzV ) grants extensive rights of use ( copying, editing, presentation, inclusion in products ) under the proviso one, that the accompanying source is mentioned and legal information in the optical context are integrated recognizable and possibly provided with a change notice will.
In Switzerland, the accessibility to the basic geodata ( within the meaning of the Swiss concept of spatial base data ) largely by the Federal Act on Geoinformation ( Geoinformation Act, GeoIG, SR 510.62 ) is regulated, which the cantons have connected with additional law enforcement enactments. Here, the basic geodata are listed under federal law (as well as by the cantons in their legislative area) in a catalog of basic spatial data and made transparent with their legal attributes, explicitly here the admission is regulated. With this regulation, the right to access to basic geodata (according GeoIG Art. 10-15) dealing with the data protection has been largely dealt with legally.