Arc/Info ASCII Grid File .ASC, .AIG, .AGR, .GRD Description


The ASC Arc/Info ASCII filter imports and exports ASC Arc/Info ASCII grid files.


File Description

An Esri grid is a raster GIS file format developed by Esri. The ASCII format is also known as Arc/Info ASCII grid. The ASCII format is used as an elevation grid exchange, or export format, with a simple ASCII file structure.


File Format

The first six lines of the file indicate the reference of the grid, followed by the values listed in the order they would appear (left to right and top to bottom).



ncols         4

nrows         6

xllcorner     0.0

yllcorner     0.0

cellsize      50.0

NODATA_value -9999

 -9999 -9999 5 2

-9999 20 100 36

3 8 35 10

32 42 50 6

88 75 27 9

13 5 1 -9999



·      ncols are the numbers of rows (represented as integers);

·      and nrows are the numbers of rows (represented as integers);

·      xllcorner and yllcorner are the western (left) X coordinate and southern (bottom) Y coordinates, such as easting and northing (represented as real numbers with an optional decimal point)

·      cellsize is the length of one side of a square cell (a real number)

·      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 real numbers (with optional decimal point, if needed) and are delimited using a single space character.


File Name Extensions



Import Method

Choose the File | Import command.


Export Method

Select a lattice or image module and choose the File | Save Data command.


ESRII ASCII Grid Format Warning Dialog

When exporting, the ESRII ASCII Grid Format Warning dialog may appear.

Esri ASCII Grid Format Warning
ESRII ASCII Grid Format Warning dialog


Click the Yes button to continue export. Click the No button to abort the export.



See Also

File Format Chart

File | Import

File | Save Data