r3.in.ascii - GRASS GIS manual
Author: GRASS Development Team
Description: r3.in.ascii: Converts a 3D ASCII raster text file into a (binary) 3D raster map.
Keywords: raster3d, import, voxel, conversion, ASCII

## NAME

r3.in.ascii - Converts a 3D ASCII raster text file into a (binary) 3D raster map.

## KEYWORDS

raster3d, import, voxel, conversion, ASCII

## SYNOPSIS

r3.in.ascii
r3.in.ascii --help
r3.in.ascii input=name output=name [null_value=string] [type=string] [precision=string] [compression=string] [tiledimension=XxYxZ] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

### Flags:

--overwrite
  Allow output files to overwrite existing files
--help
  Print usage summary
--verbose
  Verbose module output
--quiet
  Quiet module output
--ui
  Force launching GUI dialog

### Parameters:

input=name [required]
  Name of input file to be imported
  '-' for standard input
output=name [required]
  Name for output 3D raster map
null_value=string
  String representing NULL value data cell (use 'none' if no such value)
  Default: *
type=string
  Data type used in the output raster3d map
  Options: default, double, float
  Default: default
precision=string
  Number of digits used as mantissa in the internal map storage, 0 -23 for float, 0 - 52 for double, max or default
  Default: default
compression=string
  The compression method used in the output raster3d map
  Options: default, zip, none
  Default: default
tiledimension=XxYxZ
  The dimensions of the tiles used in the output raster3d map (XxYxZ or default: 16x16x8)
  Default: default

## DESCRIPTION

r3.in.ascii allows a user to create a (binary) GRASS 3D raster map layer from a 3D ASCII raster input file.

The tiledimension parameter defines the dimension of the tiles used in the output file. The format is: XxYxZ

The nv parameter specifies which value to convert to NULL-value. If the specified value is none, no conversion is performed. Default is none.

## NOTES

The data is automatically imported into the correct internal coordinate system, that is visualized in the following picture, independently from the specified ordering in the ASCII input file:

The volume coordinate system and tile layout of the imported voxel map

## NOTES

The format of the 3D ASCII file:

    version: "grass7"
    order:   "nsbt" or "nstb" or "snbt" or "sntb"
    north:   floating point
    south:   floating point
    east:    floating point
    west:    floating point
    top:     floating point
    bottom:  floating point
    rows:    integer
    cols:    integer
    levels:  integer

The version and order option have been introduced in GRASS 7 in June 2011. The version option is self explaining. The order option specifies the row and depth order of the data in the input file. The supported row/depth ordering is documented in the r3.out.ascii manual page. The order of the data in the input file does not specify the data order in the generated output 3D raster map which is in any case north -> south, west -> east, bottom -> top order. So dependent on the order information the data is automatically imported into the correct internal coordinate system.

The version and order options are not mandatory. In case no version and order option is specified, the default GRASS 6 ASCII format is assumed.

This header is followed by the cell values in floating point format organized in rows with constant col and level coordinate. The rows are organized by constant level coordinate. Individual cell values are separated by space or CR.

## EXAMPLES

4x3x2 sample. Note in case no specific ordering is specified in the input file the upper-left (NW) corner of the bottom level comes first. The according order option is: nsbt for north -> south, bottom -> top ordering. This is identical with r.in.ascii for single level data. So the y coordinate is 0 at the northern edge. north: 3.0
south: 0.0
east: 4.0
west: 0.0
top: 2.0
bottom: 0.0
rows: 3
cols: 4
levels: 2
w111x1,y1,z1 w211x2,y1,z1 w311x3,y1,z1 w411x4,y1,z1
w121x1,y2,z1 w221x2,y2,z1 w321x3,y2,z1 w421x4,y2,z1
w131x1,y3,z1 w231x2,y3,z1 w331x3,y3,z1 w431x4,y3,z1
w112x1,y1,z2 w212x2,y1,z2 w312x3,y1,z2 w412x4,y1,z2
w122x1,y2,z2 w222x2,y2,z2 w322x3,y2,z2 w422x4,y2,z2
w132x1,y3,z2 w232x2,y3,z2 w332x3,y3,z2 w432x4,y3,z2

Note that unit tests for r3.in.ascii are implemented in the test.r3.out.ascii.sh script located in the r3.out.ascii directory.

## EXAMPLES

Please refer to the detailed examples in r3.out.ascii.

## AUTHORS

Roman Waupotitsch, Michael Shapiro, Helena Mitasova, Bill Brown, Lubos Mitas, Jaro Hofierka, Sören Gebbert

## SEE ALSO

r.in.ascii, r3.out.ascii, v.to.rast3, g.region

## SOURCE CODE

Available at: r3.in.ascii source code (history)

Accessed: Sunday Jun 21 14:59:04 2026

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