r3.out.ascii(1grass) GRASS GIS User's Manual r3.out.ascii(1grass)
NAME
r3.out.ascii - Converts a 3D raster map layer into a ASCII text file.
KEYWORDS
raster3d, export, output, voxel, conversion, ASCII
SYNOPSIS
r3.out.ascii
r3.out.ascii --help
r3.out.ascii [-hrdcm] input=string [output=name] [precision=integer]
[null_value=string] [--overwrite] [--help] [--verbose] [--quiet]
[--ui]
Flags:
-h
Suppress printing of header information
-r
Switch the row order in output from north->south to south->north
-d
Switch the depth order in output from bottom->top to top->bottom
-c
Print grass6 compatible format. Flags -d and -r are ignored.
-m
Use 3D raster mask (if exists) with input map
--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=string [required]
3D raster map to be converted to ASCII
output=name
Name for ASCII output file
precision=integer
Number of decimal places for floats
Options: 0-20
Default: 8
null_value=string
String representing NULL value
Default: *
DESCRIPTION
r3.out.ascii exports a 3D raster map in ASCII format. The input parame-
ter is a valid 3D raster map in the current mapset search path. The
output parameter is the name of an ASCII file which will be written in
the current working directory.
If output is not specified then standard output (stdout) is used. The
-h flag may be used to suppress header information. The module is sen-
sitive to region settings (set with g.region).
The -c flag will create GRASS 6 r3.in.ascii compatible output.
NOTES
The default format of the exported ASCII file is equivalent to that re-
quired by r3.in.ascii. In particular, files output by r3.out.ascii with
header information may be converted back to 3D raster maps with
r3.in.ascii.
The format of the ASCII file is:
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 options have been introduced in GRASS 7 in June
2011. The order option describes the order of rows and depths in the
output. It is possible to create output of different row order using
the -r flag and output of different depths order using the -d flag.
The default order is:
west -> east for columns
north -> south for rows
bottom -> top for depths
This header is followed by the cell values in floating point format or-
ganized in rows with constant col and level coordinate. The rows are
organized by constant level coordinate. Individual cell values are sep-
arated by space or CR. Cell values are exported as a series of hori-
zontal slices in row-major order. The data starts with the upper left
corner (NW) at the bottom of the data set. The values at the following
coordinates are exported:
(x, y + rows, z) (x + 1, y + rows, z) ... (x + cols, y + rows, z)
(x, y + rows, z) (x + 1, y + rows - 1, z) ... (x + cols, y + rows - 1, z)
. . .
. . .
. . .
(x, y, z + depths) (x + 1, y, z + depths) ... (x + cols, y, z + depths)
This order is compatible with the r.in.ascii row -> column ordering.
Supported orders are:
• nsbt: north -> south and bottom -> top ordering which is the
default (no flags)
• snbt: south -> north and bottom -> top ordering using -r flag
• nstb: north -> south and top -> bottom ordering using -d flag
• sntb: south -> north and top -> bottom ordering using -rd flag
The internal storage scheme of 3D raster maps is visualized in the fol-
lowing picture:
The coordinate system and tile layout of a voxel map in
GRASS
One level maps can be imported with r.in.ascii (2D raster) using the
default nsbt order and removing the header lines "version", "order",
"top", "bottom" and "levels".
Example
We define a small region with 4 columns, 3 rows and 2 depths (4x3x2)
and export it using different ordering definitions:
g.region res3=1 t=2 b=0 w=0 e=4 s=0 n=3
r3.mapcalc "simple_example = row() + col() + depth()"
Default order:
r3.out.ascii input=simple_example dp=0
version: grass7
order: nsbt
north: 3.000000
south: 0.000000
east: 4.000000
west: 0.000000
top: 2.000000
bottom: 0.000000
rows: 3
cols: 4
levels: 2
3 4 5 6
4 5 6 7
5 6 7 8
4 5 6 7
5 6 7 8
6 7 8 9
Inverse row order (-r)
r3.out.ascii input=simple_example dp=0 -r
version: grass7
order: snbt
north: 3.000000
south: 0.000000
east: 4.000000
west: 0.000000
top: 2.000000
bottom: 0.000000
rows: 3
cols: 4
levels: 2
5 6 7 8
4 5 6 7
3 4 5 6
6 7 8 9
5 6 7 8
4 5 6 7
Inverse depth order (-d)
r3.out.ascii input=simple_example dp=0 -d
version: grass7
order: nstb
north: 3.000000
south: 0.000000
east: 4.000000
west: 0.000000
top: 2.000000
bottom: 0.000000
rows: 3
cols: 4
levels: 2
4 5 6 7
5 6 7 8
6 7 8 9
3 4 5 6
4 5 6 7
5 6 7 8
Inverse row and depth order (-rd)
r3.out.ascii input=simple_example dp=0 -rd
version: grass7
order: sntb
north: 3.000000
south: 0.000000
east: 4.000000
west: 0.000000
top: 2.000000
bottom: 0.000000
rows: 3
cols: 4
levels: 2
6 7 8 9
5 6 7 8
4 5 6 7
5 6 7 8
4 5 6 7
3 4 5 6
SEE ALSO
r3.in.ascii, r.out.ascii, g.region
AUTHORS
Roman Waupotitsch, Michael Shapiro, Helena Mitasova, Bill Brown, Lubos
Mitas, Jaro Hofierka, Sören Gebbert
SOURCE CODE
Available at: r3.out.ascii source code (history)
Accessed: unknown
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GRASS 7.8.7 r3.out.ascii(1grass)
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