Editing GIS file format (section)

==Raster formats==
{{further|Raster graphics|Data model (GIS)#Raster data model}}
[[Image:geabios3d.jpg|framed|right|Digital elevation model, map (image), and vector data]]
Like any digital image, raster GIS data is based on a regular tessellation of space into a rectangular grid of rows and columns of ''cells'' (also known as [[pixel]]s), with each cell having a measured value stored. The major difference from a photograph is that the grid is [[Georeferencing|registered]] to geographic space rather than a field of view. The [[Spatial resolution|resolution]] of the raster data set is its cell width in ground units.

Because a grid is a sample of a continuous space, raster data is most commonly used to represent [[Field (geography)|geographic fields]], in which a property varies continuously or discretely over space. Common examples include [[remote sensing]] imagery, [[Digital elevation model|terrain/elevation]], [[population density]], [[Weather map|weather and climate]], [[Soil map|soil properties]], and many others. Raster data can be images with each pixel (or cell) containing a color value. The value recorded for each cell may be of any [[level of measurement]], including a discrete qualitative value, such as land use type, or a continuous quantitative value, such as temperature, or a [[Nullable type|null]] value if no data is available. While a raster cell stores a single value, it can be extended by using raster bands to represent RGB (red, green, blue) colors, colormaps (a mapping between a thematic code and RGB value), or an extended attribute table with one row for each unique cell value.  It can also be used to represent discrete [[Geographic feature]]s, but usually only in exigent circumstances.

Raster data is stored in various formats; from a standard file-based structure of TIFF, JPEG, etc. to [[binary large object]] (BLOB) data stored directly in a [[relational database management system]] (RDBMS) similar to other vector-based feature classes. Database storage, when properly indexed, typically allows for quicker retrieval of the raster data but can require storage of millions of significantly sized records.

===Raster format examples===
*ADRG – [[National Geospatial-Intelligence Agency]] (NGA)'s ARC Digitized Raster Graphics<ref>{{cite web |title=Arc Digitized Raster Graphic (ADRG) |publisher=[[Library of Congress]] |work=Digital Preservation |date=2011-09-25 |url=http://www.digitalpreservation.gov/formats/fdd/fdd000282.shtml |accessdate=2014-03-13}}</ref>
*[[Binary file]] – An unformatted file consisting of raster data written in one of several [[data type]]s, where multiple band are stored in BSQ (band sequential), BIP (band interleaved by pixel) or BIL (band interleaved by line). Georeferencing and other metadata are stored one or more [[sidecar file]]s.<ref>{{cite web | title=Various Supported GDAL Raster Formats |url=http://www.gdal.org/frmt_various.html }}</ref>
*[[Digital raster graphic]] (DRG) – digital scan of a paper [[USGS]] [[topographic map]]
*ECRG – [[National Geospatial-Intelligence Agency]] (NGA)'s Enhanced Compressed ARC Raster Graphics (better resolution than CADRG and no color loss)
*[[ECW (file format)|ECW]] – Enhanced Compressed Wavelet (from ERDAS). A compressed wavelet format, often lossy.
*[[Esri grid]] – proprietary [[binary data|binary]] raster format used by [[Esri]] since the mid-1980s
*[[GeoTIFF]] – [[TIFF]] variant enriched with GIS relevant metadata, especially [[georeferencing]]. An open format that has become one of the most common formats for data sharing.
*IMG – [[ERDAS IMAGINE]] image file format
*[[JPEG2000]] – Open-source raster format. A compressed format, allows both lossy and lossless compression.
*[[MrSID]] – Multi-Resolution Seamless Image Database (by Lizardtech). A compressed wavelet format, allows both lossy and lossless compression.
*[[netCDF]]-CF – netCDF file format with [[Climate and Forecast Metadata Conventions|CF medata conventions]] for earth science data. Binary storage in open format with optional compression. Allows for direct web-access of subsets/aggregations of maps through [[OPeNDAP]] protocol.
*RPF – Raster Product Format, military file format specified in [[United States Military Standard|MIL-STD-2411]]<ref>{{cite web |title=Raster Product Format |publisher=[[Library of Congress]] |work=Digital Preservation |date=2011-10-27 |url=http://www.digitalpreservation.gov/formats/fdd/fdd000298.shtml |accessdate=2014-03-13}}</ref>
**CADRG – Compressed ADRG, developed by [[National Geospatial-Intelligence Agency|NGA]], nominal compression of 55:1 over ADRG (type of Raster Product Format)
**[[Controlled Image Base|CIB]] – Controlled Image Base, developed by [[National Geospatial-Intelligence Agency|NGA]] (type of Raster Product Format)
*[[USGS DEM]] – The [[USGS]]' Digital Elevation Model
**[[GTOPO30]] – Large complete Earth elevation model at 30 arc seconds, delivered in the USGS DEM format
*[[DTED]] – [[National Geospatial-Intelligence Agency]] (NGA)'s Digital Terrain Elevation Data, the military standard for elevation data
*[[World file]] – [[Georeference|Georeferencing]] a raster image file (e.g. JPEG, BMP)