GeoTIFF

GeoTIFF is a public domain metadata standard which allows georeferencing information to be embedded within a TIFF file. The potential additional information includes map projection, coordinate systems, ellipsoids, datums, and everything else necessary to establish the exact spatial reference for the file. The GeoTIFF format is fully compliant with TIFF 6.0, so software incapable of reading and interpreting the specialized metadata will still be able to open a GeoTIFF format file.[1]

An alternative to the "inlined" TIFF geospatial metadata is the *.tfw World File sidecar file format which may sit in the same folder as the regular TIFF file to provide a subset of the functionality of the standard GeoTIFF described here.

History

The GeoTIFF format was originally created by Dr. Niles Ritter while he was working at the NASA Jet Propulsion Laboratory.[2] The reference implementation code was released mostly as public domain software with some parts under a permissive X license.[3] On September 14th, 2019, the Open Geospatial Consortium published the OGC GeoTIFF standard,[4] which defines the Geographic Tagged Image File Format (GeoTIFF) by specifying requirements and encoding rules for using the Tagged Image File Format (TIFF) for the exchange of georeferenced or geocoded imagery. The OGC GeoTIFF 1.1 standard formalizes the existing community GeoTIFF specification version 1.0 and aligns it with the continuing addition of data to the EPSG Geodetic Parameter Dataset.

Cloud Optimised GeoTIFF

"Cloud Optimized GeoTIFF" (COG) is a standard based on GeoTIFF, designed to make it straightforward to use GeoTIFFs hosted on HTTP webservers, so that users and software can make use of partial data within the file without having to download the entire file.[5][6] It is designed to work with HTTP range requests, and specifies a particular layout of data and metadata within the GeoTIFF, such that clients can predict which range of bytes they need to download. COG is simply a specialisation of GeoTIFF, so COG files are TIFF files.

COG was developed within the Open Source Geospatial Foundation/GDAL project, starting in around 2016.[7] The COG format can be read and written by many common geographic software tools including GDAL, QGIS, and GeoTrellis.[8] Various providers now supply some of their data in COG format, including Google[8] and DigitalGlobe.[9]

See also

References
  1. Sk. Sazid Mahammad, R. Ramakrishnan, GeoTIFF - A standard image file format for GIS applications. Retrieved on 2017-02-01.
  2. Ruth, Mike (February 2005). Who owns the GeoTIFF format? Archived 2014-10-19 at the Wayback Machine. Retrieved on 2008-02-16.
  3. libgeotiff125.zip on remotesensing.org in license "libgeotiff Licensing - All the source code in this toolkit are either in the public domain, or under an X style license. In any event it is all considered to be free to use for any purpose (including commercial software). No credit is required though some of the code requires that the specific source code modules retain their existing copyright statements. The CSV files, and other tables derived from the EPSG coordinate system database are also free to use. In particular, no part of this code is "copyleft", nor does it imply any requirement for users to disclose this or their own source code. All components not carrying their own copyright message, but distributed with libgeotiff should be considered to be under the same license as Niles' code."
  4. Open Geospatial Consortium, OGC GeoTIFF Standard. Retrieved on 2019-11-07.
  5. Cloud Optimized GeoTIFF website
  6. COG technical specification (on Github)
  7. OSGeo wiki page with early documentation of COG format
  8. Chris Holmes (2018), "Cloud Optimized GeoTIFF Advances"
  9. DigitalGlobe blog: Cloud optimized GeoTIFFs and the path to accessible satellite imagery analytics
  • OGC GeoTIFF formalizes the existing community GeoTIFF specification version 1.0 and aligns it with the continuing addition of data to the EPSG Geodetic Parameter Dataset.
  • GeoTIFF.io Open-source website for viewing and analyzing GeoTIFF files
  • Official website
  • "GeoTIFF - A standard image file format for GIS applications". Geospatial World. Sep 1, 2009. Details backwards compatible GeoTIFF extensions to the TIFF file format and header
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