An Esri grid is a raster

GIS file format A GIS file format or geospatial file format is a standard for encoding geographical information into a computer file. It is a specialized type of file format for use in geographic information systems (GIS), remote sensing image processing tools, a ...

developed by

Esri Environmental Systems Research Institute, Inc., doing business as Esri (), is an American Multinational corporation, multinational geographic information system (GIS) software company headquartered in Redlands, California. It is best known for ...

, which has two formats: #A proprietary '' binary'' format, also known as an ''ARC/INFO GRID'', ''ARC GRID'' and ''many'' other variations #A non-proprietary ''

ASCII ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control c ...

'' format, also known as an ''ARC/INFO ASCII GRID'' The formats were introduced for ARC/INFO. The binary format is widely used within Esri programs, such as ArcGIS, while the ASCII format is used as an exchange, or export format, due to the simple and portable ASCII file structure. The grid defines geographic space as an array of equally sized

square In geometry, a square is a regular polygon, regular quadrilateral. It has four straight sides of equal length and four equal angles. Squares are special cases of rectangles, which have four equal angles, and of rhombuses, which have four equal si ...

grid points arranged in rows and columns. Each grid point stores a numeric value that represents a geographic attribute (such as

elevation The elevation of a geographic location (geography), ''location'' is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational equipotenti ...

or surface slope) for that unit of space. Each grid cell is referenced by its x,y coordinate location.

File formats

ASCII

In Esri grid data, the first six lines indicate the reference of the grid, followed by the values listed in "English reading order" (left-right and top-down). For example, consider a grid, shown to the left. This could be encoded into an ASCII grid file, that would look like: where *''ncols'' and ''nrows'' are the numbers of columns and rows, respectively (represented as

integer An integer is the number zero (0), a positive natural number (1, 2, 3, ...), or the negation of a positive natural number (−1, −2, −3, ...). The negations or additive inverses of the positive natural numbers are referred to as negative in ...

s); *''xllcorner'' and ''yllcorner'' are the western (left) ''x''-

coordinate In geometry, a coordinate system is a system that uses one or more numbers, or coordinates, to uniquely determine and standardize the position of the points or other geometric elements on a manifold such as Euclidean space. The coordinates are ...

and southern (bottom) ''y''-coordinates, such as easting and northing (represented as

real number In mathematics, a real number is a number that can be used to measure a continuous one- dimensional quantity such as a duration or temperature. Here, ''continuous'' means that pairs of values can have arbitrarily small differences. Every re ...

s with an optional decimal point), **when the data points are cell-centered ''xllcenter'' and ''yllcenter'' are used to indicate such registration. *''cellsize'' is the

length Length is a measure of distance. In the International System of Quantities, length is a quantity with Dimension (physical quantity), dimension distance. In most systems of measurement a Base unit (measurement), base unit for length is chosen, ...

of one side of a square cell (a real number); and, *''nodata_value'' is the value that is regarded as "missing" or "not applicable"; this line is optional, but highly recommended as some programs expect this line to be declared (a real number). The remainder of the file lists the raster values for each cell, starting at the upper-left corner. These

s (with optional decimal point, if needed) are delimited using a single

space character A whitespace character is a character data element that represents white space when text is rendered for display by a computer. For example, a ''space'' character (, ASCII 32) represents blank space such as a word divider in a Western scri ...

Binary format

A binary Esri grid is stored in several files contained in at least two directories: the ''name'' directory and an ''info'' directory, where ''name'' has strict naming conventions. The grid name must begin with an alphabetic character and must only include alphanumeric characters or the underscore ("_") character. A multiple-band grid (a collection of grids also known as a "stack" in ArcGIS) cannot have more than 9 characters in its file name, and a single-band raster dataset cannot have more than 13 characters.

References

{{reflist ;Binary grid
Arc/INFO GRID file structure
for

GDAL The Geospatial Data Abstraction Library (GDAL) is a computer software library for reading and writing raster and vector geospatial data formats (e.g. shapefile), and is released under the permissive X/MIT style free software license by the ...

;ASCII grid
ASCII grid format
for

GIS raster file formats