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NAME

       r3.out.netcdf  - Export a 3D raster map as netCDF file.

KEYWORDS

       raster3d, export, 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

       Last changed: $Date: 2012-06-14 11:20:10 +0200 (Thu, 14 Jun 2012) $

SOURCE CODE

       Available at: r3.out.netcdf source code (history)

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