Provided by: grass-doc_7.8.2-1build3_all 
NAME
r3.out.netcdf - Export a 3D raster map as netCDF file.
KEYWORDS
raster3d, export, output, netCDF, voxel
SYNOPSIS
r3.out.netcdf
r3.out.netcdf --help
r3.out.netcdf [-pm] input=name output=name [null=float] [--overwrite] [--help] [--verbose]
[--quiet] [--ui]
Flags:
-p
Export projection information as wkt and proj4 parameter
-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=name [required]
Name of input 3D raster map
output=name [required]
Name for netCDF output file
null=float
The value to be used for null values, default is the netCDF standard
DESCRIPTION
The module r3.out.netcdf exports a 3D raster map as netCDF file. Maps are valid 3D raster maps in the
current mapset search path. The output parameter is the name of a netCDF file that will be written in the
current working directory. The module is sensitive to mapset region settings (set with g.region) and the
vertical unit settings of the 3D raster map. The vertical unit can be set with r3.support.
Note
The resulting netCDF file will have time as third dimension in case a temporal vertical unit is specified
for the input map, otherwise the third dimension is assumed as spatial. If the 3D raster map has a time
stamp with absolute time, the start time will be used as starting point for the netCDF time series. If
the absolute time stamp is missing the date "Jan. 01. 1900 00:00:00" will be used as default. In case of
relative time stamp no start time is set in the netCDF file. The number of depths of the 3D raster map
are the number of time slices in the netCDF file. You can use t.rast.to.rast3 to convert a space time
raster dataset into a 3D raster map representing a space time voxel cube, then export the raster time
series as netCDF file.
Spatial coordinates are exported as cell centered coordinates. The projection can be optionally stored in
the metadata as crs attributes . The netCDF projection metadata storage follows the spatial_ref
GDAL/netCDF suggestion here and the netCDF CF 1.6 convention here using WKT projection information.
Additional a PROJ.4 string is stored in the crs attribute section. The export of projection parameters
is suppressed when the XY-projection is set.
The range of the 3D raster map is set in the netCDF output file. Optionally a the netCDF missing value
and _FillValue can be set using the null option. As default the netCDF floating point _FillValues are
used to fill empty cell.
The netCDF library must be installed on the system and activated at configuration time to compile this
module.
Examples
g.region s=-90 n=90 w=-180 e=180 b=0 t=5 res=10 res3=10 tbres=1 -p3
#####################################################################
# We create a simple volume map with floating point values
#####################################################################
r3.mapcalc --o expr="volume_float = float(col() + row() + depth())"
r3.info volume_float
+----------------------------------------------------------------------------+
| Layer: volume_float Date: Thu Jun 14 08:40:56 2012 |
| Mapset: PERMANENT Login of Creator: soeren |
| Location: TestLL |
| DataBase: /1/soeren/grassdata |
| Title: volume_float |
| Units: none |
| Vertical unit: units |
| Timestamp: none |
|----------------------------------------------------------------------------|
| |
| Type of Map: 3d cell Number of Categories: 0 |
| Data Type: FCELL |
| Rows: 18 |
| Columns: 36 |
| Depths: 5 |
| Total Cells: 3240 |
| Total size: 10114 Bytes |
| Number of tiles: 1 |
| Mean tile size: 10114 Bytes |
| Tile size in memory: 12960 Bytes |
| Number of tiles in x, y and z: 1, 1, 1 |
| Dimension of a tile in x, y, z: 36, 18, 5 |
| |
| Projection: Latitude-Longitude (zone 0) |
| N: 90N S: 90S Res: 10 |
| E: 180E W: 180W Res: 10 |
| T: 5 B: 0 Res: 1 |
| Range of data: min = 3 max = 59 |
| |
| Data Source: |
| |
| |
| |
| Data Description: |
| generated by r3.mapcalc |
| |
| Comments: |
| r3.mapcalc expression="volume_float = float(col() + row() + depth())" |
| |
+----------------------------------------------------------------------------+
#####################################################################
# We use the netCDF ncdump tool to have a look at the header
# and coordinates of the exported netCDF file
#####################################################################
r3.out.netcdf --o input=volume_float output=test_float.nc
ncdump -c test_float.nc
netcdf test_float {
dimensions:
longitude = 36 ;
latitude = 18 ;
z = 5 ;
variables:
float longitude(longitude) ;
longitude:units = "degrees_east" ;
longitude:long_name = "Longitude values" ;
longitude:standard_name = "longitude" ;
longitude:axis = "X" ;
float latitude(latitude) ;
latitude:units = "degrees_north" ;
latitude:long_name = "Latitude values" ;
latitude:standard_name = "latitude" ;
latitude:axis = "Y" ;
float z(z) ;
z:units = "meter" ;
z:long_name = "z coordinate of projection" ;
z:standard_name = "projection_z_coordinate" ;
z:positive = "up" ;
z:axis = "Z" ;
float volume_float(z, latitude, longitude) ;
volume_float:valid_min = 3.f ;
volume_float:valid_max = 59.f ;
// global attributes:
:Conventions = "CF-1.5" ;
:history = "GRASS GIS 7 netCDF export of r3.out.netcdf" ;
data:
longitude = -175, -165, -155, -145, -135, -125, -115, -105, -95, -85, -75,
-65, -55, -45, -35, -25, -15, -5, 5, 15, 25, 35, 45, 55, 65, 75, 85, 95,
105, 115, 125, 135, 145, 155, 165, 175 ;
latitude = 85, 75, 65, 55, 45, 35, 25, 15, 5, -5, -15, -25, -35, -45, -55,
-65, -75, -85 ;
z = 0.5, 1.5, 2.5, 3.5, 4.5 ;
}
#####################################################################
# Exporting the projection specific settings and a null value
#####################################################################
r3.out.netcdf --o -p null=-1 input=volume_float output=test_float.nc
ncdump -c test_float.nc
netcdf test_float {
dimensions:
longitude = 36 ;
latitude = 18 ;
z = 5 ;
variables:
char crs ;
crs:crs_wkt = "GEOGCS[\"wgs84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS_1984\",6378137,298.257223563]],PRIMEM[\"Greenwich\",0],UNIT[\"degree\",0.0174532925199433]]" ;
crs:spatial_ref = "GEOGCS[\"wgs84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS_1984\",6378137,298.257223563]],PRIMEM[\"Greenwich\",0],UNIT[\"degree\",0.0174532925199433]]" ;
crs:crs_proj4 = " +proj=longlat +no_defs +a=6378137 +rf=298.257223563 +towgs84=0.000,0.000,0.000" ;
float longitude(longitude) ;
longitude:units = "degrees_east" ;
longitude:long_name = "Longitude values" ;
longitude:standard_name = "longitude" ;
longitude:axis = "X" ;
float latitude(latitude) ;
latitude:units = "degrees_north" ;
latitude:long_name = "Latitude values" ;
latitude:standard_name = "latitude" ;
latitude:axis = "Y" ;
float z(z) ;
z:units = "meter" ;
z:long_name = "z coordinate of projection" ;
z:standard_name = "projection_z_coordinate" ;
z:positive = "up" ;
z:axis = "Z" ;
float volume_float(z, latitude, longitude) ;
volume_float:valid_min = 3.f ;
volume_float:valid_max = 59.f ;
volume_float:missing_value = -1.f ;
volume_float:_FillValue = -1.f ;
volume_float:grid_mapping = "crs" ;
// global attributes:
:Conventions = "CF-1.5" ;
:history = "GRASS GIS 7 netCDF export of r3.out.netcdf" ;
data:
longitude = -175, -165, -155, -145, -135, -125, -115, -105, -95, -85, -75,
-65, -55, -45, -35, -25, -15, -5, 5, 15, 25, 35, 45, 55, 65, 75, 85, 95,
105, 115, 125, 135, 145, 155, 165, 175 ;
latitude = 85, 75, 65, 55, 45, 35, 25, 15, 5, -5, -15, -25, -35, -45, -55,
-65, -75, -85 ;
z = 0.5, 1.5, 2.5, 3.5, 4.5 ;
}
#####################################################################
# Assigning time as vertical unit and setting an absolute time stamp
#####################################################################
r3.timestamp map=volume_float date=’1 Jan 2001/5 Jan 2001’
r3.support map=volume_float vunit="days"
r3.out.netcdf --o -p null=-1 input=volume_float output=test_float.nc
ncdump -c test_float.nc
netcdf test_float {
dimensions:
longitude = 36 ;
latitude = 18 ;
time = 5 ;
variables:
char crs ;
crs:crs_wkt = "GEOGCS[\"wgs84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS_1984\",6378137,298.257223563]],PRIMEM[\"Greenwich\",0],UNIT[\"degree\",0.0174532925199433]]" ;
crs:spatial_ref = "GEOGCS[\"wgs84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS_1984\",6378137,298.257223563]],PRIMEM[\"Greenwich\",0],UNIT[\"degree\",0.0174532925199433]]" ;
crs:crs_proj4 = " +proj=longlat +no_defs +a=6378137 +rf=298.257223563 +towgs84=0.000,0.000,0.000" ;
float longitude(longitude) ;
longitude:units = "degrees_east" ;
longitude:long_name = "Longitude values" ;
longitude:standard_name = "longitude" ;
longitude:axis = "X" ;
float latitude(latitude) ;
latitude:units = "degrees_north" ;
latitude:long_name = "Latitude values" ;
latitude:standard_name = "latitude" ;
latitude:axis = "Y" ;
int time(time) ;
time:units = "days since 2001-01-01 00:00:00" ;
time:long_name = "Time in days" ;
time:calendar = "gregorian" ;
time:positive = "up" ;
time:axis = "T" ;
float volume_float(time, latitude, longitude) ;
volume_float:valid_min = 3.f ;
volume_float:valid_max = 59.f ;
volume_float:missing_value = -1.f ;
volume_float:_FillValue = -1.f ;
volume_float:grid_mapping = "crs" ;
// global attributes:
:Conventions = "CF-1.5" ;
:history = "GRASS GIS 7 netCDF export of r3.out.netcdf" ;
data:
longitude = -175, -165, -155, -145, -135, -125, -115, -105, -95, -85, -75,
-65, -55, -45, -35, -25, -15, -5, 5, 15, 25, 35, 45, 55, 65, 75, 85, 95,
105, 115, 125, 135, 145, 155, 165, 175 ;
latitude = 85, 75, 65, 55, 45, 35, 25, 15, 5, -5, -15, -25, -35, -45, -55,
-65, -75, -85 ;
time = 0, 1, 2, 3, 4 ;
}
SEE ALSO
t.rast.to.rast3, r3.in.ascii, g.region
AUTHORS
Sören Gebbert
SOURCE CODE
Available at: r3.out.netcdf source code (history)
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