NAME
r.buildvrt.gdal - Build GDAL Virtual Rasters (VRT) over GRASS GIS raster maps
KEYWORDS
raster,
virtual,
gdal,
patch
SYNOPSIS
r.buildvrt.gdal
r.buildvrt.gdal --help
r.buildvrt.gdal [-mr] [input=name[,name,...]] [file=name] [vrt_directory=name] output=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags:
- -m
- Read data range from metadata
- WARNING: metadata are sometimes approximations with wrong data range
- -r
- Create fast link without data range
- WARNING: some modules do not work correctly without known data range
- --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[,name,...]
- Name of input raster map(s)
- file=name
- Name of input file
- vrt_directory=name
- Directory to store GDAL VRT files in. Default is: $GISDBASE/$PROJECT/$MAPSET/gdal
- output=name [required]
- Name for output raster map
r.buildvrt.gdal builds GDAL virtual rasters over GRASS GIS raster
maps and links them to the mapset with
r.external. The module is
written as a workaround for a limitation in GRASS GIS Virtual Rasters (VRT)
format with GDAL-linked raster maps (through
r.external /
r.external.out. In that case GRASS GIS Virtual Rasters currently
show performance issues. See:
#4345
For the resulting maps GDAL VRT text files are created either in a
directory named "gdal" in the current mapset or in a user-defined
vrt_directory. Those files are not removed when the raster map is
removed and the user is responsible for removing them when needed.
r.buildvrt.gdal uses the Python bindings for
GDAL and requires the
GDAL-GRASS driver to include raster maps in native GRASS format in
GDAL VRTs.
# Create external example data
regs='s,0,1000
n,500,1500'
eval `g.gisenv`
external_path="${GISDBASE}/${LOCATION}/${MAPSET}/.tmp/vrt"
mkdir -p "$external_path"
for reg in $regs
do
r=$(echo $reg | cut -f1 -d",")
s=$(echo $reg | cut -f2 -d",")
n=$(echo $reg | cut -f3 -d",")
g.region -g n=$n s=$s w=0 e=1000 res=1
r.external.out format=GTiff options="compress=LZW,PREDICTOR=3" \
directory="$external_path"
r.mapcalc --o --v expression="${r}_${s}_gtiff_ntfs=float(x()*y())"
done
# Run performance tests
g.region -g n=1500 s=0 w=0 e=1000 res=1
format_type=gtiff_ntfs
rmaps=$(g.list type=raster pattern="*_*_${format_type}", sep=",")
# Using GRASS GIS VRT
r.buildvrt --o --v input="$rmaps" output=vrt_${format_type}
time r.univar map=vrt_${format_type}
# Using GDAL VRT
r.buildvrt.gdal --o --v input="$rmaps" output=vrt_${format_type}_gdal
time r.univar map=vrt_${format_type}_gdal
r.buildvrt,
r.patch,
r.external,
r.external.out
Stefan Blumentrath
SOURCE CODE
Available at:
r.buildvrt.gdal source code
(history)
Latest change: Monday Sep 23 23:52:52 2024 in commit: 14d31c9015fe6d6de27d6a24cc13fcfddeac447f
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GRASS Development Team,
GRASS GIS 8.4.1dev Reference Manual