GIS data format

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Standardized data formats of geographic information systems are referred to as GIS data format . Various data formats are used in a GIS to collect , edit, organize, analyze and present geographical data . There are vector-based and raster-based formats. All geometry data can be supplemented by factual data (attributes). Official geo-informatics standards are published, for example, by the International Organization for Standardization (ISO) or the Open Geospatial Consortium . The commercial manufacturers of these systems introduced their own data formats. De facto industry standards are also often found. Many file formats from open source projects are compatible with their commercial equivalent.

Currently, three large classes of file types can be formed in relation to the use of different data formats: ESRI - ArcGIS file types , which are mostly compatible with open source programs (DIVA-GIS, GRASS GIS , QGIS etc.). The file types that have been standardized by the Open Geospatial Consortium OGC and are mostly used in open source programs. And finally, special data formats that only work in the system of the respective developer, such as IMAGINE, raster data format from ERDAS Imagine .

File extensions and formats for vector data

file extension Art description developer compatibility
.isam. / .bgrund vector ALK / DFK in Baden-Württemberg uses the Index Sequential Access Method (ISAM). This is just a method of accessing records. IBM in the late 1960s / Land Survey Office BaWü Compatibility unknown
Coverage vector The model on which the coverage is based contains various geometry types (feature classes) within a folder structure (feature dataset). The geometry types are mutually dependent. Originally developed by ESRI in 1981 for ArcInfo ArcGIS
.dgn vector Intergraph / Bentley Standard File Format ? Compatibility unknown
.dwg vector AutoCAD Drawing, drawing file, which can also be imported into GIS programs and processed further. Autodesk ArcGIS
.dxf vector Drawing Interchange Format Autodesk ArcGIS
.E00 vector ArcInfo export format ArcGIS Compatibility unknown
.edb vector Uniform database interface (EDBS), ( ALK / DFK and ATKIS ) ? Compatibility unknown
.gdb Vector, raster File geodatabase version 9.2 or higher, container format used with ArcGIS ESRI ArcGIS
.gdf vector Geographic Data Files is a conceptual and logical data model with the definition of a non-binary standard file exchange format for vectorized map data, especially street maps. ISO / DIS 14825: 2011 (GDF5.0 edition of the standard replaces GDF4.0 from 2004). Traditionally, GDF files have fixed-width fields of 80 characters per line. The individual records can be continued with continuation records. The latest revision of the GDF standard by ISO now also provides for XML and SQL-based formats. The data is stored in three levels: 1. Topology, 2. Functions, 3. Complex functions. Car navigation industry Compatibility unknown
.gml vector Files of the markup language Geography Markup Language for exchanging spatial objects ( "features"). GML allows the transmission of objects (with attributes, relations and geometries) including non-conventional data such as sensor data. Current version: Version 3.2.1 Open Geospatial Consortium OGC, ArcGIS
.gpkg vector GeoPackage describes an exchange format for geodata. The geodata are stored in a SQLite database in a manner defined by the standard . Geometries are coded as WKT or WKB and stored in the database. Open Geospatial Consortium OGC, QGIS , ArcGIS, GDAL
.gpx vector The GPS Exchange Format (GPX) is a data format for storing geospatial data (GPS data) and is based on the general XML standard. An XML schema describes the elements and the structure of the GPS Exchange format. TopoGrafix OGC, ESRI
.iff vector Interchange File Format is a planar bitmap graphic format (with 24/32 bit) originally Electronic Arts OGC, ArcGIS
.ili / ilt / itf / xtf vector INTERLIS transfer format ? OGC, ESRI
.kml / .kmz vector Keyhole Markup Language is the markup language (that describes the content of spatial data) for the client components of the programs Google Earth and Google Maps . KML follows the XML syntax and is version 2.2. KMZ is identical in content to KML, but compressed in the ZIP file format . Open Geospatial Consortium OGC, ESRI
.lay vector RegioGraph Layer, system for economic market analysis GfK GeoMarketing GmbH ?
.mdb vector The Microsoft Access Database can create a file-based proprietary database. ArcGIS uses this format as a personal geodatabase Microsoft ArcGIS
.mif / .mid vector A map and database file format for MapInfo. Consists of the two non-binary files: The MIF file contains the metadata and feature definitions as well as the coordinates. The MID file contains the separator-separated attributes, one line per object being used. ESRI ?
.mxd vector ArcGIS document format ESRI ESRI, OGC
.sfa vector Simple Feature Access for displaying geographic data (points, lines, polygons and additionally several points (MultiPoint), several lines (MultiLineString), several polygons (MultiPolygon) and collection of these geometries (GeometryCollection)). Comparable to shapefiles from ArcGIS. Open Geospatial Consortium OGC
.shp + .shx + .dbf vector Shapefiles , for displaying geographic data (points, lines, polygons). Shapefiles consist of i. d. Usually at least three files:
  • .shp is used to save the geometry data
  • .dbf factual data in dBASE format
  • .shx is used as an index of the geometry to link the factual data (also called attribute data)
 By ESRI for ArcView ESRI, OGC
.geojson vector GeoJSON , a JSON-based file format for points, lines, polygons independent, later IETF OGC

Other formats

File extensions and formats for raster data

file extension Art description developer compatibility
.gif Raster data Graphics Interchange Format . Generates a good lossless compression for pictures with little color depth (up to 256 (= 28) different colors per single picture). Compuserve ArcGIS, OGC
.gpkg Raster data GeoPackage describes an exchange format for geodata. The geodata are stored in a SQLite database in a manner defined by the standard . Raster data are encoded as PNG or JPEG and stored in a BLOB in the database. Open Geospatial Consortium OGC, QGIS , ArcGIS, GDAL
.grid Raster data ESRI Grid ESRI Compatibility unknown
.img Raster data Raster data format of the ERDAS Imagine system , especially for the evaluation of RS images Erda's Imagine ArcGIS
.jpg Raster data JPEG File Interchange Format , often together with world file (extension JFW) Joint Photographic Experts Group ESRI, OGC
.tif / .tiff Raster data Tagged Image File Format , often together with world file (extension .tfw) or GeoTIFF . The latter has developed as a quasi-standard for displaying raster data. The image information can be displayed in any program that supports the normal TIFF standard. Intergraph ArcGIS, OGC, Adobe Photoshop etc. a.

Enhancements for georeferencing data

World File

A world file is an additional file with the georeference of a raster image. Own geodata are not included. The file type was introduced by the ESRI company as a supplement for simple image files. The filename extension is derived from the image type and is, for example, .jgw, .pgw, .gfw or .tfw for JPEG, PNG, GIF or TIFF image data.

GeoTIFF

GeoTIFF has developed as a quasi-standard for the representation of raster data and is supported by most GIS programs that process raster data as well as some image processing programs (including Adobe Photoshop). The image information can be displayed in any program that supports the normal TIFF standard.

A GeoTIFF is a special form of a TIFF image. Since the TIF format allows loss-free storage, it is well suited for processing geographic data, since satellite and aerial images or other raster data often require a high level of imaging accuracy.

The specialty of GeoTIFF compared to the normal TIF format is that special data about the georeference is embedded in the image file in addition to the visible raster data. This includes coordinates for georeferencing the image section and for the map projection used: The file contains specific information about the coordinate reference system .

In contrast to GeoJPEG or normal TIF format, the information is not stored in a separate file ( world file ), but directly in the meta tags of the image, whereby six tags are used for the geographic information. If necessary, these tags can be expanded to include additional fields.

GeoTIFF files can be compressed with all algorithms that are possible for the TIF format, in addition to various lossless methods, also with lossy JPEG compression, with which a significant reduction in file size can be achieved at the expense of image quality. However, not every application supports all compression algorithms permitted by the TIF format.

The initiative to create the GeoTIFF format goes back to the Intergraph company, which began development in the early 1990s.

Other formats

Optional files

literature

  • Andrea, Fitzke, Zipf (Eds.) (2009): OpenGIS essentials. An overview of the OGC and ISO geo-standards. Christine Andrae: Spatial Schema, ISO 19107 and ISO 19137 presented and explained. Wichmann-Verlag , Heidelberg. ISBN 9783879074730
  • Wolfgang Liebig (2006): ArcGIS-ArcView9 personal geodatabase - practical introduction Points Verlag Norden , Halmstad. ISBN 3981045300

Web links

Individual evidence

  1. ↑ Can be generated and read with ESRI Spatial Analyst