DESCRIPTION

This module exports a space time raster dataset as a tar archive. The archive contains the raster maps either as geotiff files or as GRASS binary files exported using r.out.bin. The map specific color tables are exported as well in case of geotiff files. In addition several meta data files are created in the archive that describe the temporal layout. All time stamps are stored in the file "list.txt", for each map one row. The name of the map, the start time and the end time are written. In case of a time instance, the start time is equal to the end time. The "init.txt" files stores the temporal type, the number of maps, the chosen export format and some other metadata. The "proj.txt" files stores the projection information as proj4 string of the location the space time raster dataset was exported from. The file "readme.txt" describes the file format. The output of r.info is stored in "metadata.txt".

The tar archive can be compressed using the compress option. Gzip and bzip2 are available. A where option can be specified, to export only a subset of the space time dataset. Archives exported with t.rast.export can be importet with t.rast.import.

EXAMPLE

In this example we create 7 raster maps that will be registered in a single space time raster dataset named precipitation_daily using a daily temporal granularity. The names of the raster maps are stored in a text file that is used for raster map registration. We export the created space time raster dataset and will have a look at some files that are created: 

MAPS="map_1 map_2 map_3 map_4 map_5 map_6 map_7"

for map in ${MAPS} ; do
    r.mapcalc --o expr="${map} = 1" 
    echo ${map} >> map_list.txt 
done

t.create type=strds temporaltype=absolute \
         output=precipitation_daily \
         title="Daily precipitation" \
         description="Test dataset with daily precipitation"

t.register -i type=rast input=precipitation_daily \
           file=map_list.txt start="2012-08-20" increment="1 days"

t.rast.export input=precipitation_daily output=precipitation_daily.tar

tar xvf precipitation_daily.tar
map_1.tif
map_1.color
map_2.tif
map_2.color
map_3.tif
map_3.color
map_4.tif
map_4.color
map_5.tif
map_5.color
map_6.tif
map_6.color
map_7.tif
map_7.color
list.txt
proj.txt
init.txt
readme.txt
metadata.txt


cat init.txt
stds_type=strds
format=GTiff
temporal_type=absolute
semantic_type=mean
number_of_maps=7
north=80.0
south=0.0
east=120.0
west=0.0


cat proj.txt
+proj=longlat
+no_defs
+a=6378137
+rf=298.257223563
+towgs84=0,0,0,0,0,0,0


cat list.txt
map_1|2012-08-20 00:00:00|2012-08-21 00:00:00
map_2|2012-08-21 00:00:00|2012-08-22 00:00:00
map_3|2012-08-22 00:00:00|2012-08-23 00:00:00
map_4|2012-08-23 00:00:00|2012-08-24 00:00:00
map_5|2012-08-24 00:00:00|2012-08-25 00:00:00
map_6|2012-08-25 00:00:00|2012-08-26 00:00:00
map_7|2012-08-26 00:00:00|2012-08-27 00:00:00


cat readme.txt 
This space time raster dataset was exported with t.rast.export of GRASS GIS 7

Files:
       *.tif  -- GeoTIFF raster files
     *.color  -- GRASS GIS raster color rules
     proj.txt -- Projection information in PROJ.4 format
     init.txt -- GRASS GIS space time raster dataset information
     list.txt -- Time series file, lists all maps by name with interval
                 time stamps in ISO-Format. Field separator is |
 metadata.txt -- The output of t.info
   readme.txt -- This file

SEE ALSO

t.rast.import, t.create, t.info

AUTHOR

Sören Gebbert

Last changed: $Date$