Geographic information system

Geographic information systems (GIS ) Geographical information systems or Spatial Information Systems (RIS ) are information systems for the collection, processing, organization, analysis and presentation of spatial data. Geographic information systems include the corresponding hardware, software, data and applications.

• 4.1 Modelling 4.1.1 Data Model
• 4.1.2 Data Structure Model
• 4.1.3 topology
• 4.1.4 dimensions

• 5.1 Data Collection
• 5.2 Data Processing 5.2.1 conversion 5.2.1.1 Vector - raster and raster to vector conversion

• 5.3.1 geodatabases

• 5.4.1 Queries and selections
• 5.4.2 buffer
• 5.4.3 Processing of boundaries
• 5.4.4 intersection
• 5.4.5 merging, merging
• 5.4.6 Network Analysis
• 5.4.7 interpolation

• 5.5.1 generalization

• 6.1 Land Information Systems ( LIS)
• 6.2 Municipal Information System ( HIS)
• 6.3 Environmental Information System ( UIS)
• 6.4 Soil Information System (BIS )
• 6.5 Network Information System (NIS )
• 6.6 Information System (FIS )
• 6.7 GIS in archeology
• 6.8 GIS with event planning
• 6.9 GIS in Transport and Logistics (GIS -T)

• 7.1 OGC standards
• 7.2 ISO 191xx series

Areas of application

Geographic information systems are used in many fields, including geography, environmental sciences, archeology, marketing, cartography, urban planning, criminology (→ Crime cards ), logistics and resource management. Using a GIS, it is disaster protection officer for example possible to compile information for evacuation plans. Environmental authorities to determine which wetlands are particularly prone areas. Marketing departments can find out in which areas new customers can be won.

History

Prehistory

Even before about 15,500 years recorded Cro -Magnon hunters images of their prey to the walls of the Lascaux caves. Together with the animal images path and line drawings have been found which can be interpreted as migration routes of these animals. Although simple in comparison with modern techniques, these early representations of two elements of the structure of modern geographic information systems (an image associated with attribute information ) dar.

1854 was designed by the physician John Snow a map of cholera cases in London. He then asked each case as a point at the corresponding position dar. This application was therefore possibly the first of its kind Snow's studies of the distribution of cholera led to the source of the disease, a contaminated water pump in the center of the cholera map. While the basic elements of topology and theme were previously known in cartography, John Snow's map is characterized by the fact that he first used this cartographic methods not only for visualization but for cluster analysis of spatial phenomena.

At the beginning of the 20th century, the photolithography has been developed. This technique splits the contents of the card into multiple layers. With the rapid development of computer hardware in the 1960s, the first universal card creation applications emerged.

Development of modern GIS

In 1962, the first modern GIS in Ottawa by the Department of Forestry and Rural Development has been developed. Dr. Roger Tomlinson developed a GIS called "Canada Geographic Information System" ( CGIS ). It had functions for the storage, analysis and processing of data from the "Canada land Inventory". The aim was to determine the capacity of the land ( soil, agriculture, forests, wildlife, waterfowl, land use ) at a scale of 1:50,000. These data were categorized into grades, to facilitate analysis. CGIS was the first true GIS and an evolution of the pure mapping applications, as it / includes numerous additional functions such as overlay, measurement, and digitizing scanning. It supported a national coordinate system, processed lines as arcs with a real topology and stored the attributes of the spatial information separately in separate files. Through this development, Tomlinson became known as the "father of GIS ". CGIS was used until the 1990s and was the largest digital land resource database in Canada. It was developed as a mainframe system to support national and regional resource planning and management. One of its strengths was the nationwide analysis of complex data. CGIS was never available in commercial form.

In 1964, Howard T. Fisher the " Laboratory for Computer Graphics and Spatial Analysis " at the " Harvard Graduate School of Design ". There are numerous important theoretical concepts for the processing of spatial data have been developed. Already in the 1970s the team had published numerous pioneering program code portions and software systems such as " SYMAP ", " GRID " and " Odyssey ". These were sources of inspiration for future commercial developments.

In the 1980s emerged with M & S Computing (later Intergraph ), ESRI and CARIS important commercial producers of geospatial software. Your GIS included numerous functions. They build on the traditional approach of separating spatial data from attribute data, but store the attribute data in databases.

At the same time began the " U.S. Army Corp of Engineering Research Laboratory " in Champaign, Illinois with the development of a free GIS called GRASS GIS.

In the late 80s and 90s, the programs offered initially grew by a strong increase in the use of GIS on UNIX, and later on Windows computers.

End of the twentieth century, the GIS technology developed towards the Internet. Therefore it was necessary to standardize data formats and transfer.

Today there are more and more open source GIS that run on many operating systems and can be adapted for special requirements.

GIS software

In the commercial sector commercial GIS dominate. Among the most famous manufacturers include Autodesk ( Topobase and Map3D ), Bentley Systems ( Microstation ), ESRI ( ArcGIS ), Intergraph ( GeoMedia ), Manifold System, Mapinfo, Disy.net and Small World. These manufacturers usually offer a complete range of systems in various stages of development. Authorities and the military often use special specially created, adapted (eg CAIGOS, GEOgraFIS, POLYGIS ), or open source software products. The best-known open source GIS GRASS and QGIS are, both projects of the Open Source Geospatial Foundation, and OpenJUMP and DIVA - GIS. There are numerous other systems or GIS tools such as SAGA GIS, FWTools, GeoTools or OpenLayers. On the German market the products of Autodesk, ESRI, CAIGOS and Mapinfo dominate. Open Source GIS play a subordinate role.

In the area of ​​online GIS Google Maps dominate with Google Earth as desktop access software, Bing Maps, HERE, Yandex.Maps and OpenStreetMap as an open source project.

Distributed service-based architectures enable a simplified, cost- spatial data distribution. Most desktop GIS support access to web-based standardized maps and spatial data services. Current developments in the area of ​​Web-GIS point to an increased importance of GIS on the Internet.

Geoportals as a specific form of web GIS web portals are for a search for and access to geographic information and services (representation, editing, analysis) using a web browser.

Geodata

Modeling

Data model

Describing data models, which data can be stored in an information system, and how this data is structured. It involves information about real objects (people, parcels, rivers). These objects are described by selected attributes. For example, you can assign all parcels attributes district number, corridor, parcel number and type of use. The mentioned properties are those that are unique ( state, district, corridor, hallway piece counter, parcel denominator in the format 00/0000/000/00000/00000 ) describe an object of type Parcel and by its nature. This is also called " descriptive data", " thematic data", " factual data " or " attribute data ".

The "traditional" information systems are limited to the purely administrative and processing of factual data. In GIS attribute data nor the so-called geometry data are compared. They describe the location, shape, orientation and size of objects (see also spatial objects). A distinction is vector data and raster data. Vector data representing the object geometry using graphical elements (eg points, lines, arcs ). Raster or pixel data arise mostly from digital images (maps images or air or satellite imagery).

For vector data to the geometry of a parcel are thus obtained in the form of the boundary point coordinates and geometry of the boundary lines ( line, arc of a circle ). The extract of a digital aerial image ( usually in the form of an ortho-photos ) represents the parcel geometry in the form of raster data.

In addition to the information of the individual objects store information systems are still relationships between these objects. It may be appropriate logical relations or spatial relationships or both relationship categories to be mapped. A proper logical relationship can be prepared, for example, between parcels and People: A "person" (object) "owns " ( proper logical relationship ) of the " parcel " (object). The appropriate logical relations can be evaluated in an information system; Example: Query all parcels of a certain person.

Spatial ( = topological ) relationships go, for example, parcels with each one: a parcel (more precisely: the parcel area) " is neighbor" ( topological relationship ) of another parcel. Also, topological relations can be evaluated in a GIS. Examples: The query of all neighboring land to a parcel.

GIS dominate the integrated management of the property and geometry data as well as appropriate logical and topological relationships. This queries or reports can also refer to both types of information. Example: Query the owner data ( proper data-related aspect ) on all parcels that are adjacent to a selected parcel ( topological aspect ) and have an area greater than 1000 m² ( geometry -related aspect ) is.

Data structure model

A data structure model specifies how objects and their relationships in an information system, in this case specifically a GIS, can be mapped. For the storage of the object attributes and relationships, for example, the relational model has prevailed. All attributes of similar objects are maintained in tables; the same applies to the relations between the objects.

Vector-based data structure models make it possible to describe the object geometry using geometric elements ( eg, points, arcs, lines ); these elements can be ordered or unordered grouping through to higher quality geometries summarized (eg polylines or surfaces ). Vector data can be relatively easily link with factual data.

The grid-based data structure model has only a single data structure element, namely the grid element, called pixels or " pixel ", depending on the raster fashion. The grid elements can be assigned to two properties: the geometric and radiometric resolution. The geometric resolution specifies the length and width has a grid element in nature; the radiometric resolution refers to the distinct gray values ​​per grid element.

Topology

The topology refers to the spatial relationship of geo-objects to each other (neighborhood relations ). In contrast to the geometry, which affects the shape and absolute position in space, topological relationships between geo-objects are independent of dimensions as the distance. The most important topological relations between two geo-objects A and B by Egenhofer are:

• A is disjoint from B
• A is within B
• B is within A
• A covers B
• B covers A
• A meets B
• A similar B

Dimensions

Depending on the task geographic information systems to manage and edit spatial data in one to four dimensions:

• Along a line ( road or railway line, manhole, border, etc. ),
• On a surface (2D, what is the most common case ),
• 3D object or 2D time series, or
• Combined in space and time ( 4D)

In older systems, the form of primitives were embedded only in the two-dimensional space due to the lack of 3D data.

In a transition phase, the altitude was added as an attribute of two-dimensional objects. Since this but no 3D embedding is still carried out, it is called in this case only by a zweieinhalbdimensionalen embedding.

In modern applications, for example in the geosciences, the objects are embedded in three-dimensional space.

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 ISO 19113 has been listed features for the quality of spatial data in the ISO standard ISO.

Terms of Use

The rights to geospatial information derived primarily from copyright. If geospatial be performed by public law, in addition also rights under the Surveying and Geoinformation right may exist. The rights of "everyone" allow their own localization, as well as maps of public places to make to use the data itself and spread. Projects such as OpenStreetMap follow this development path.

Functions of GIS

Geographic Information Systems expand its use of the classical map. In addition to the visualization, there are numerous functions for the analysis of spatial data.

Data collection

Modern GIS use digital information, different data collection methods used for their detection. Especially in the early days of the digitization of paper maps and survey plans was the most common method of data capture. Purpose is transferred ( in GIS or CAD programs ), the analog information into digital form using a digitizing board and geo-referencing. Increasingly important is the on-screen digitization of satellite and aerial images. The scanned or already existing digital images are used directly on the screen as a template for digitization.

Another method of data collection is the data collection in the field with GPS devices. Using DGPS useful accuracies can be achieved for surveying purposes.

Data processing

Conversion

Spatial data can be stored in many different file formats, and ( geo) database. Virtually every commercial GIS manufacturer supplies their own formats. Geographic information systems provide therefore normally functions to convert spatial data into different file formats.

Since digital data can be collected in many different ways and stored, it can happen that two data sources are not compatible. The geographic information system must therefore be able to convert spatial data from one structure to the other. Thus, a GIS can be used to satellite images reversed vector in transform ( grid structure) in vector or raster structures structures.

Vector - raster and raster to vector conversion

General irregular surfaces are difficult to be approximated by a grid, as can be eliminated more output information in a grid cell. Is especially clear this problem with coarser cell structures, but also a fine grid does not solve the fundamental problem. A frequently used approach is that the grid cell gets the value of the output surface, which has the largest proportion of the cell. It may also be useful to determine certain characteristics that are to be assigned a priority or higher weight of a cell.

In the raster to vector conversion is made between two types:

• From adjacent cells with the same attribute values ​​vector objects to be generated.
• Existing geo-objects should be assigned attributes from raster data sets. This type of raster to vector conversion is based in practice almost exclusively on the so-called point method. This geo-objects are blended with the centers of the grid cells. If the center of the cell is within the geoobjects, the value of the cell is used to calculate the value of geoobjects (e.g., by averaging).

Coordinate transformation

Spatial data are available in a wide variety of coordinate systems. Therefore, a central function of geographic information systems is the coordinate transformation. The coordinate transformation may be " on-the- fly", that is, done on the fly, or in a separate step.

Georeferencing

Under georeferencing, geocoding and localization refers to the allocation of spatial reference information about a record. For the preparation of relating to space, in many cases, transformations and conversions as well as interpolations are necessary. These include the elimination of geometrical distortions, fitting of the data in a selected coordinate system, and / or mutual adjustment of two data layers.

Georeferencing of images is often based on interpolation using control points and then resampling, that is, the reorganization of the data / objects (see rectification ).

Personal data can be located on the address. These comprehensive address databases are necessary in order to obtain, for example, the road segment values ​​depending on the task.

Data Management

With growing amounts of data and the increasing dissemination of geographic information systems is becoming increasingly important to manage spatial data efficiently. For this it is necessary to detect and continuously update metadata. Some GIS to provide built-in functions other systems leave it up to the user to manage metadata using other software products.

Geodatabases

For the storage of material and geometry data (primarily the vector data) used at the beginning of the GIS era only a few GIS - based systems marketable database systems (such as dBase or Oracle). A variety of systems based on proprietary database management systems. Today, the use of market- major relational and object-relational database systems for spatial data management has prevailed.

Conventional databases can not effectively manage spatial data. Therefore, there are many commercial and open source databases extensions for the management of spatial data. Examples of spatial databases are: Oracle Spatial, PostGIS and SpatiaLite. Some manufacturers offer interfaces to different databases.

Spatial analyzes

The concept of spatial or GIS analysis is not clearly defined. For an analysis of raw data must be converted into useful information to make more effective decisions. Analysis can uncover the circumstances and relationships that would otherwise have remained invisible. In the literature, the term is used in the following areas:

• Spatial data manipulation ( buffer, ...)
• Spatial data analysis - descriptive and examining
• Spatial statistical analysis (eg interpolation by kriging )
• Spatial modeling for spatial predictions

Further distinction can be made between the qualitative and quantitative spatial analysis.

For spatial analysis, it is important to know the form in which data is stored and how the spatial phenomena are represented. The quality of the output data affect the analysis significantly. Both the suitability of the data as well as the choice of suitable analytical zones are of great importance.

Among the methods of spatial analysis: queries, measurement, transformations, descriptive summary, optimization, hypothesis testing and modeling.

The results of spatial analysis change if the location of the objects is modified. To avoid misinterpretation, any spatial analysis requires a proper interpretation of the results.

Queries and selections

Queries are used in solving questions on product or geographic criteria and selection of the results on the map.

Examples

• Objectively: How many people live in a certain city?
• Spatially: How many and which cities are located on the banks of a certain river?

Buffer

The buffer function ( engl. buffer) allows the formation of buffer zones around geo-objects of arbitrary dimension. Depending on the dimension is referred to as point, line or area buffers.

In the production of the buffer zones an area is generated around the selected geoobjects. The buffer zones surround the geoobject and surrounding areas within a certain distance ( fixed value or as a function of the attributes of the spatial objects ) from the original geoobject. The original geo-objects are not modified during this operation.

Buffers are not only graphics, but objects with which one can perform analyzes such as intersections. It is possible to create a plurality of buffers, and this object is different from weighted ( for example, various protection zone categories).

Processing limits

When processing limits only the geometry of a data layer is changed. The attributes and attribute values ​​are not touched. Only the surface area and the extent of the resulting faces will be recalculated. Possible modifications are:

• Merging geometries
• Stamping out of areas
• Splitting into several smaller areas
• Cutting out / delete parts from the inside of an area

Intersection

With intersection is defined as the superposition of layers threads (layers) or object groups. Using Boolean operations are formed from the output data levels new objects that combine the attributes of the output objects. It is a new level of data. The output data levels are not changed.

Merging, merging

This feature combined with the attribute items such as the removal of " splinters polygons " are formed by blending.

Network analysis

The analysis of networks is one of the core applications of geographic information systems.

Applications of networks are the modeling of transportation systems such as roads or rail networks, as well as line networks, such as Pipeline networks or telecommunications transmission networks. Networks are sets of nodes and edges. They belong to the graph, in practice usually only occur unbalanced and weighted graphs. The analysis of networks based on graph theory. Networks have a node-edge - node topology and thus build on the vector model.

Network edges may represent any road, railway or shipping lines for a transport network as well as conducting paths of an electric transmission network or the flow of a river network. The nodes of the network are, for example, Stops, or general linking sites such as intersections. The network elements can be assigned to properties that can be included depending on the task in analyzes. The assessment of the edges is usually by the path length between two nodes. For car navigation, the travel time can be used for evaluation.

Are network analysis to address the following issues carried out:

• Determining the shortest path between two points
• Problem of the traveling salesman
• Determination of catchment areas

Interpolation

Powerful GIS provide methods for spatial interpolation and modeling of surfaces in space. Starting from a few, distributed in space points ( xi, yi) with attribute values ​​zi ( for example, temperature measurements or height information ) are arbitrary points (xk, yk ) attribute values ​​zk are determined. These will be closed by means of interpolation of the known values ​​of zi on the unknown values ​​zk. It is implicitly assumed that those sites ( or the associated values) affect this value to a new location more that are closer to him. Interpolation amount to a determination of weighted averages.

Typical uses are calculating a spatial precipitation or temperature distribution, a terrain or ground water or surface of the spatial distribution of concentrations in the soil.

The spatial interpolation methods include:

• Trend surface analysis
• Spatial interpolation by averaging
• Triangulation and Thiessen polygons ( Voronoi diagram and Dirichlet decomposition )

Presentation

Play The possibilities of representation and presentation in GIS a crucial role and are therefore very comprehensive. Here are some important examples:

• Automatic creation of legend, scale bar, north arrow, and the other edge of the map details
• User-definable color and patterning, as well as symbolic representations
• Ein-/Ausblendung and combination of different layers ( raster and vector data)
• 3D displays, digital terrain models, " Drape " (merged with raster or vector data 3D - model)
• Animations (fly over terrain and the like)
• Terrain sections / profiles
• Integration of charts, image or audio data

Generalization

Summary, generalization, simplification and triaging of objects. Generalization of the Erfassungsgeneralisierung addition is necessary if the standard is reduced to prevent degradation of the readability.

Automation

For recurring tasks, it is useful to automate this by creating the necessary processes are combined into macros. Such tasks may include:

• Plots of maps and plans in accordance with a particular hand section under the same boundary conditions
• Nachattributierung imported data
• Specific periodic evaluations for regular reports
• Regular data handoffs to other offices or companies through defined interfaces
• Testing procedures for data consistency
• Inclusion of external data maintained property

Conditions for Automatisierbakeit are:

• A macro language with loops, conditions and input options
• Consistent, non-redundant data ( Exception: if the consistency is not checked by the macro ).
• Software readable, classified data attributes can be selected which ones.

Characteristics of geographic information systems

Land Information Systems ( LIS)

Manage land information systems detailed spatial data, especially data base ( primary, directly measured / collected data ) that are structured großmaßstäbig. Land information systems are usually of surveying authorities ( and Cadastral Office) established and managed. They relate primarily to the mapping the earth's surface in the form of digital maps and land.

Municipal Information System ( HIS)

Municipal information systems GIS in municipalities. A central component of KIS are the basic geodata from the LIS ( Automated Real Estate Map and Automated Real Estate Register in Germany, Digital cadastral and land database in Austria ) and aerial photographs. They allow the employees of a municipality quick access to information about a parcel (owners, area size, use, ...).

Besides this basis KIS contain a variety of additional layers. A municipal Environmental Information System ( kui ), for example, a set of tools for tasks of the municipality in the area of ​​environment, the data on all sectors of the environment spatially, temporally and factually holds, processed and currently holds. The first additional layers that have been recorded, mostly contained the line land for water, sewer, gas and electricity. Today, there are various additional layers such as green space land, tree register, cemetery cadastre, cadastral Playground and Others

Environmental Information System ( UIS)

Environmental information systems used to provide environmental information. They are usually made of multiple environmental databases on various topics and provide powerful access and data analysis for the derivation of environmental information. Environmental information systems are used for collection, storage, processing and presentation of space -, time- and content-based data describing the state of the environment with regard to hazards and stresses, and form the basis for measures of environmental protection. They are usually from many different expert information systems (FIS ).

Their tasks range from the detection of radioactivity, the control of the environmental media air, water and soil to habitat mapping and biodiversity conservation. They are used for emergency preparedness, the administrative enforcement and the public information on the environment.

Because of the variety of potential users of a UIS exist diverse, partly diverging requirements on the characteristics of a UIS. UIS be used as information systems in the administration and in private sector companies ( so-called Operational Environmental Information Systems ). Early adopters were, for example, environmental agencies such as the Federal Environmental Agency (UBA ) or state environmental ministries and their subordinate offices of the Länder.

Soil Information System (BIS )

Soil information systems include geological data. They are complex and can be built up in interdisciplinary collaboration.

A soil information system in the narrow sense (A, CH) data concerning the regional distribution of soil types and their properties such as soil structure, organic matter content, pH and soil severity. The soil maps, in addition to the type of soil also show soil pollution or the risk of erosion.

A soil information system in a wider sense (eg the BIS NRW or the Lower Saxony soil information system NiBiS ) also includes data on the geological structure of the uppermost crust and hydrogeology, resilience, engineering geology and geochemistry. The data contained Bore descriptions, analysis, data and maps of different scales and themes.

Network Information System (NIS )

A network information system is supply and disposal companies to document their management portfolio. Besides the graphical representation of the line profiles and their condition records of the nature and technical data in the information system to be managed. Network information systems are offered by many companies and engineering plans - for example in the management of research before building work - used.

Information System (FIS )

Technical information systems constitute a special class of geo- information systems dar. This includes the special applications that are not covered by the previous forms. They are information systems that support specialist tasks and are required to meet specific business requirements, such as civil engineering, geography, geology, hydrology, avalanche and environmental protection, transport planning, tourism, leisure and route planning. The main customers for specialized applications are municipalities.

GIS in archeology

Also in archaeological research geographic information systems are used. For example, archaeological sites are linked to the information about their environment, such as water, raw materials and food removal, soil quality, climate zone. Here, especially surveyors, geographers and archaeologists working together in interdisciplinary groups.

In the archaeological heritage of different countries and states ( pioneer in Europe, inter alia, the Netherlands) GIS is primarily for inventory collection, visualization and analysis used. For sites and related information can for example be quickly mapped and compared with planned construction projects for the planning. Recently, GIS are increasingly used for the calculation of location criteria as yet unknown sites (so-called prediction models, eg Archäoprognose Brandenburg).

GIS with event planning

GIS also serve as a tool for the planning of major events. In the GEOLYMPIA project of GIS-Cluster Salzburg University demonstrates the improved planning and implementation of major sporting events. The optimizations have been used in events such as the World Cycling Championships in 2006, the 2008 European Football Championships or the Olympics in 2014 for planning purposes. The group developed modules for scenarios for the sustainable use of resources and to increase the security of such major events.

GIS in Transport and Logistics (GIS -T)

Geographic Information Systems for Transportation and Logistics (GIS -T) include the methods and applications of GIS technologies for problems in the transport sector. An important application is the creation and maintenance of street graphs.

Standards for geographic information systems

The most important standards in the field of GIS, the standards of the Open Geospatial Consortium ( OGC) and the ISO 191xx series.

OGC standards

OGC interface and protocol specifications provide communication between different Web-GIS, location-based services and standard IT technologies. The standards enable the development of complex spatial applications and their functions provide a variety of applications. Examples of OGC specifications are Web Map Service (WMS ), Web Feature Service (WFS ) and Simple Feature Access.

ISO 191xx series

Standards of this series:

• ISO 19107
• ISO 19109
• ISO 19111
• ISO 19115
• ISO 19136