GRASS logo

NAME

r.mapcalc.tiled - Runs r.mapcalc in parallel over tiles.

KEYWORDS

raster, algebra, tiling

SYNOPSIS

r.mapcalc.tiled
r.mapcalc.tiled --help
r.mapcalc.tiled expression=string [output=name] width=integer height=integer overlap=integer [nprocs=integer] [processes=integer] [mapset_prefix=string] [--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:

expression=string [required]
Expression to send to r.mapcalc
output=name
Name of raster output map resulting from expression
width=integer [required]
Width of tiles (columns)
Default: 1000
height=integer [required]
Height of tiles (rows)
Default: 1000
overlap=integer [required]
Overlap of tiles
Default: 0
nprocs=integer
Number of r.mapcalc processes to run in parallel
Options: 1-
processes=integer
This option is obsolete and replaced by nprocs
Number of r.mapcalc processes to run in parallel, use nprocs option instead
Options: 1-
mapset_prefix=string
Mapset prefix

Table of contents

DESCRIPTION

r.mapcalc.tiled cuts a raster input map into tiles and runs r.mapcalc over these tiles before patching the result together into a single output raster map.

The user provides the map calculation expression. The output map name is automatically extracted from that expression by extracting the string before the '='. If the expression is more complex, the user can also provide the the output map name with the parameter output

Tiles can be defined with the width, height and overlap parameters. If nprocs is higher than one, these tiles will be processed in parallel.

The mapset_prefix parameter ensures that the temporary mapsets created during the tiled processing have unique names. This is useful if the user runs r.mapcalc.tiled several times in parallel (e.g. in an HPC environment).

NOTES

EXAMPLE

Run r.mapcalc over tiles with size 1000x1000 using 4 parallel processes (North Carolina sample dataset):
 
g.region raster=ortho_2001_t792_1m
r.mapcalc.tiled expression="bright_pixels = if(ortho_2001_t792_1m > 200, 1, 0)" \
   width=1000 height=1000 nprocs=4

SEE ALSO

r.mapcalc

AUTHOR

Moritz Lennert

SOURCE CODE

Available at: r.mapcalc.tiled source code (history)

Latest change: Wed Mar 30 10:17:35 2022 in commit: 25b0a9981b66c443a1c1af1d5f26182c93268b45


Main index | Raster index | Topics index | Keywords index | Graphical index | Full index

© 2003-2022 GRASS Development Team, GRASS GIS 8.0.3dev Reference Manual