GIS file formats

As GIS data format standardized data formats of geographic information systems are referred to. In a GIS, various data formats for recording, editing, organization, analysis and presentation of geographical data are used. There are vector-based and raster-based formats. All geometry data can be supported by physical data (attributes ). Official Geo computer science standards, for example, of the International Organization for Standardization ( ISO) or the Open Geospatial Consortium published. Of the commercial manufacturers of these systems own data formats were introduced. Frequently also the de facto industry standards are to be found. Many file formats of open source projects are compatible with their commercial equivalent.

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

  • 2.1 Extensions for georeference 2.1.1 World File
  • 2.1.2 GeoTIFF

File extensions and formats for vector data

  • . shp is used to store geometry data
  • . dbf attribute data in dBASE format
  • . shx serves as an index of the geometry used to link the attribute data (also called attribute data )

Other formats

  • DKM - for data of the Automated Property Book in Austria
  • NAS - Standards-based exchange interface, remodeling of the AFIS -ALKIS -ATKIS model
  • OVL - Overlay ( Geogrid Viewer, Top50 )
  • PMF - POLYGIS Metafile
  • SVG - Scalable Vector Graphics ( W3 Consortium)
  • SQD - SICAD / open
  • VEC / VEH - SPANS vector archive format
  • WLDGE - data for the automated real estate book in Germany

File extensions and formats for raster data

Extensions for geospatial reference

World File

No own data format but a Zusatdatei often used is World file. This is a small text file that contains georeference an image. The file type was introduced by the company ESRI as a supplement for simple image formats. The file name extension derives from the name and file type of the image file and reads, for example. Jgw. Pgw. Gfw or. Tfw for JPEG, PNG, GIF or TIFF image data.

GeoTIFF

GeoTIFF has emerged as the de facto standard for the representation of raster data and is used by most data processing raster GIS programs as well as some image editing programs (eg Adobe Photoshop) support. 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 for lossless storage, it is well suited to the management of geographic data, as it often arrives in satellite and aerial imagery or other raster data at high imaging accuracy.

The peculiarity of GeoTIFF compared to the normal TIF format is that specific data on the georeference in addition to the visible raster data embedded in the image file. These include coordinates for geo-referencing the image section and the used map projection: The file contains information specific to the coordinate reference system.

The information is being six tags are used for geo-information in contrast to the normal GeoJPEG or TIF format not in a separate file (world file), but stored directly in the meta tags of the image. If necessary, these tags are extensible with additional fields.

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

The initiative to create the GeoTIFF format goes to the company Intergraph with development beginning in the early 1990s back.

Other formats

  • CIT - Intergraph CCITT Group IV, Type 24 (CIT, COT. . ) Bentley MicroStation
  • MrSID - Multi- resolution Seamless Image Database
  • PGR - POLYGIS raster format

Optional files

  • PRJ - projection of the data ( may be part of ArcGIS shapefiles )
Geoinformation AutoCAD AutoCAD DXF Markup language Geography Markup Language GPS Exchange Format INTERLIS Keyhole Markup Language MapInfo Interchange Format Remote sensing Joint Photographic Experts Group
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