DESCRIPTION

r.out.gdal allows a user to export a GRASS raster map layer into any GDAL supported raster map format. For possible metaopt parameters see the 'supported formats' pages of GDAL. The createopt may be used to create TFW or World files ("TFW=YES", "WORLDFILE=ON").

r.out.gdal also supports the export of multiband rasters through a group (created e.g. with i.group), when the group's name is entered as input.

SUPPORTED RASTER FORMATS

The set of supported raster formats written by r.out.gdal depends on the local GDAL installation. Available may be (incomplete list):

  AAIGrid: Arc/Info ASCII Grid
  BMP: MS Windows Device Independent Bitmap
  BSB: Maptech BSB Nautical Charts
  DTED: DTED Elevation Raster
  ELAS: ELAS
  ENVI: ENVI .hdr Labelled
  FIT: FIT Image
  GIF: Graphics Interchange Format (.gif)
  GTiff: GeoTIFF
  HDF4Image: HDF4 Dataset
  HFA: Erdas Imagine Images (.img)
  JPEG2000: JPEG-2000 part 1 (ISO/IEC 15444-1)
  JPEG: JPEG JFIF
  MEM: In Memory Raster
  MFF2: Atlantis MFF2 (HKV) Raster
  MFF: Atlantis MFF Raster
  NITF: National Imagery Transmission Format
  PAux: PCI .aux Labelled
  PCIDSK: PCIDSK Database File
  PNG: Portable Network Graphics
  PNM: Portable Pixmap Format (netpbm)
  VRT: Virtual Raster
  XPM: X11 PixMap Format

NOTES

When writing out GeoTIFF format for users of ESRI software or ImageMagick, the band interleaving should be switched to pixel interleaving using createopt="INTERLEAVE=PIXEL".

To specify multiple options use a comma separated list (createopt="TFW=YES,COMPRESS=DEFLATE").

Out of the GDAL data types, the closest match for GRASS CELL, FCELL and DCELL rasters are respectively Int32, Float32 and Float64. These are not exact equivalents, but they will preserve the max possible data range and number of decimal places for each respective GRASS raster data type. Please keep in mind, that not all CELL rasters will require Int32 - e.g., 0-255 CELL raster are covered by the Byte type as well. Moreover, some GDAL-supported formats do not support all the data types possible in GDAL and GRASS. Use r.info to check the data type and range for your GRASS raster, refer to specific format documentation (GDAL website, format vendor's docs) and e.g. the Wikipedia article Typical boundaries of primitive integral types for details.

EXAMPLES

Export the integer raster roads map to GeoTIFF format:

r.out.gdal input=roads output=roads.tif type=UInt16

Export a DCELL raster map in GeoTIFF format suitable for ESRI software:

r.out.gdal in=elevation.10m out=ned_elev10m.tif type=Float64 createopt="INTERLEAVE=PIXEL,TFW=YES"

Export the floating point raster elevation map to ERDAS/IMG format:

r.out.gdal input=elevation.10m output=elev_dem10.img format=HFA type=Float32

GDAL RELATED ERROR MESSAGES

"ERROR 6: SetColorInterpretation() not supported for this dataset.": This may indicate that the color table was not written properly. But usually it will be correct and the message can be ignored.
"ERROR 6: SetNoDataValue() not supported for this dataset.": The selected output format does not support "no data". It is recommended to use a different output format.
"Warning 1: Lost metadata writing to GeoTIFF ... too large to fit in tag.": The color table metadata are too large. It is recommended to use a different output format.

REFERENCES

GDAL Pages: http://www.gdal.org

AUTHOR

Vytautas Vebra (oliver4grass at gmail.com)

Last changed: $Date$