DESCRIPTION

r.in.gdal allows a user to create a (binary) GRASS raster map layer, or imagery group, from any GDAL supported raster map format, with an optional title. The imported file may also be optionally used to create a new location.

GDAL supported raster formats

Full details on GDAL supported formats are available at:

http://www.gdal.org/formats_list.html

Selected formats of the more than 80 supported formats: 


Long Format Name                                        Code                    Creation        Georeferencing          Maximum File Size

Arc/Info ASCII Grid                                     AAIGrid                 Yes             Yes                     No limits
Arc/Info Binary Grid                                    AIG                     No              Yes                     --
AIRSAR Polarimetric                                     AIRSAR                  No              No                      --
Microsoft Windows Device Independent Bitmap (.bmp)      BMP                     Yes             Yes                     4GiB
BSB Nautical Chart Format (.kap)                        BSB                     No              Yes                     --
VTP Binary Terrain Format (.bt)                         BT                      Yes             Yes                     --
CEOS (Spot for instance)                                CEOS                    No              No                      --
First Generation USGS DOQ (.doq)                        DOQ1                    No              Yes                     --
New Labelled USGS DOQ (.doq)                            DOQ2                    No              Yes                     --
Data (.dt0, .dt1)                                       DTED                    No              Yes                     --
ERMapper Compressed Wavelets (.ecw)                     ECW                     Yes             Yes			
ESRI .hdr Labelled                                      EHdr                    No              Yes                     --
ENVI .hdr Labelled Raster                               ENVI                    Yes             Yes                     No limits
Envisat Image Product (.n1)                             Envisat                 No              No                      --
EOSAT FAST Format                                       FAST                    No              Yes                     --
FITS (.fits)                                            FITS                    Yes             No			
Graphics Interchange Format (.gif)                      GIF                     Yes             No                      2GB
Arc/Info Binary Grid (.adf)                             GIO                     Yes             Yes		     
GRASS Rasters                                           GRASS                   No              Yes                     --
TIFF / GeoTIFF (.tif)                                   GTiff                   Yes             Yes                     4GiB
Hierarchical Data Format Release 4 (HDF4)               HDF4                    Yes             Yes                     2GiB
Erdas Imagine (.img)                                    HFA                     Yes             Yes                     No limits
Atlantis MFF2e                                          HKV                     Yes             Yes                     No limits
Image Display and Analysis (WinDisp)                    IDA                     Yes             Yes                     2GB
ILWIS Raster Map (.mpr,.mpl)                            ILWIS                   Yes             Yes                     --
Japanese DEM (.mem)                                     JDEM                    No              Yes                     --
JPEG JFIF (.jpg)                                        JPEG                    Yes             Yes                     4GiB (max dimentions 65500x65500)
JPEG2000 (.jp2, .j2k)                                   JPEG2000                Yes             Yes                     2GiB
JPEG2000 (.jp2, .j2k)                                   JP2KAK                  Yes             Yes                     No limits
NOAA Polar Orbiter Level 1b Data Set (AVHRR)            L1B                     No              Yes                     --
Erdas 7.x .LAN and .GIS                                 LAN                     No              Yes                     2GB
In Memory Raster                                        MEM                     Yes             Yes                     2GiB
Atlantis MFF                                            MFF                     Yes             Yes                     No limits
Multi-resolution Seamless Image Database                MrSID                   No              Yes                     --
NDF                                                     NLAPS Data Format       No              Yes                     No limits
NITF                                                    NITF                    Yes             Yes		
NetCDF                                                  netCDF                  Yes             Yes                     2GB
OGDI Bridge                                             OGDI                    No              Yes                     --
PCI .aux Labelled                                       PAux                    Yes             No                      No limits
PCI Geomatics Database File                             PCIDSK                  Yes             Yes                     No limits
Portable Network Graphics (.png)                        PNG                     Yes             No		
PCRaster (.map)                                         PCRaster                Yes             No			
Netpbm (.ppm,.pgm)                                      PNM                     Yes             No                      No limits
RadarSat2 XML (product.xml)                             RS2                     No              Yes                     4GB
USGS SDTS DEM (*CATD.DDF)                               SDTS                    No              Yes                     --
SAR CEOS                                                SAR_CEOS                No              Yes                     --
USGS ASCII DEM (.dem)                                   USGSDEM                 No              Yes                     --
X11 Pixmap (.xpm)                                       XPM                     Yes             No

Location Creation

r.in.gdal attempts to preserve projection information when importing datasets if the source format includes projection information, and if the GDAL driver supports it. If the projection of the source dataset does not match the projection of the current location r.in.gdal will report an error message (Projection of dataset does not appear to match current location) and then report the PROJ_INFO parameters of the source dataset.

If the user wishes to ignore the difference between the apparent coordinate system of the source data and the current location, they may pass the -o flag to override the projection check.

If the user wishes to import the data with the full projection definition, it is possible to have r.in.gdal automatically create a new location based on the projection and extents of the file being read. This is accomplished by passing the name to be used for the new location via the location parameter. Upon completion of the command, a new location will have been created (with only a PERMANENT mapset), and the raster will have been imported with the indicated output name into the PERMANENT mapset.

Support for GCPs

In case the image contains GCPs they are written to a POINTS file within an imagery group. They can directly be used for i.rectify.

The target option allows you to automatically re-project the GCPs from their own projection into another projection read from the PROJ_INFO file of the location name target.

NOTES

Import of large files can be significantly faster when setting memory to the size of the input file.

The r.in.gdal command does support the following features, as long as the underlying format driver supports it:

Color Table
Bands with associated colortables will have the color tables transferred. Note that if the source has no colormap, r.in.gdal in GRASS 5.0 will emit no colormap. Use r.colors map=... color=grey to assign a greyscale colormap. In a future version of GRASS r.in.gdal will likely be upgraded to automatically emit greyscale colormaps.
Data Types
Most GDAL data types are supported. Float32 and Float64 type bands are translated as GRASS floating point cells (but not double precision ... this could be added if needed), and most other types are translated as GRASS integer cells. This includes 16bit integer data sources. Complex (some SAR signal data formats) data bands are translated to two floating point cell layers (*.real and *.imaginary).
Georeferencing
If the dataset has affine georeferencing information, this will be used to set the north, south, east and west edges. Rotational coefficients will be ignored, resulting in incorrect positioning for rotated datasets.
Projection
The datasets projection will be used to compare to the current location or to define a new location. Internally GDAL represents projections in OpenGIS Well Known Text format. A large subset of the total set of GRASS projections are supported.
Null Values
Raster bands for which a null value is recognised by GDAL will have the null pixels transformed into GRASS style nulls during import. Many generic formats (and formats poorly supported by GDAL) do not have a way of recognising null pixels in which case r.null should be used after the import.
GCPs
Datasets that have Ground Control Points will have them imported as a POINTS file associated with the imagery group. Datasets with only one band that would otherwise have been translated as a simple raster map will also have an associated imagery group if there are ground control points. The coordinate system of the ground control points is reported by r.in.gdal but not preserved. It is up to the user to ensure that the location established with i.target has a compatible coordinate system before using the points with i.rectify.

Planned improvements to r.in.gdal in the future include support for reporting everything known about a dataset if the output parameter is not set.

Error Messages

"ERROR: Input map is rotated - cannot import."
In this case the image must be first externally rotated, applying the rotation info stored in the metadata field of the raster image file. For example, the gdalwarp software can be used to transform the map to North-up (note, there are several gdalwarp parameters to select the resampling algorithm): 
gdalwarp rotated.tif northup.tif

"ERROR: Projection of dataset does not appear to match the current location."
You need to create a location whose projection matches the data you wish to import. Try using location parameter to create a new location based upon the projection information in the file. If desired, you can then re-project it to another location with r.proj. Alternatively you can override this error by using the -o flag.

"WARNING: G_set_window(): Illegal latitude for North"
Latitude/Longitude locations in GRASS can not have regions which exceed 90° North or South. Non-georeferenced imagery will have coordinates based on the images's number of pixels: 0,0 in the bottom left; cols,rows in the top right. Typically imagery will be much more than 90 pixels tall and so the GIS refuses to import it. If you are sure that the data is appropriate for your Lat/Lon location and intentd to reset the map's bounds with the r.region module directly after import you may use the -l flag to constrain the map coordinates to legal values. While the resulting bounds and resolution will likely be wrong for your map the map's data will be unaltered and safe. After resetting to known bounds with r.region you should double check them with r.info, paying special attention to the map resolution. In most cases you will want to import into the datafile's native projection, or into a simple XY location and use the Georectifaction tools (i.rectify et al.) to properly project into the target location. The -l flag should only be used if you know the projection is correct but the internal georeferencing has gotten lost, and you know the what the map's bounds and resolution should be beforehand.

EXAMPLES

GTOPO30 DEM

To avoid that the GTOPO30 data are read incorrectly, you can add a new line "PIXELTYPE SIGNEDINT" in the .HDR to force interpretation of the file as signed rather than unsigned integers. Then the .DEM file can be imported. Finally, e.g. the 'terrain' color table can be assigned to the imported map with r.colors.

GLOBE DEM

To import GLOBE DEM tiles (approx 1km resolution, better than GTOPO30 DEM data), the user has to download additionally the related HDR file(s). Finally, e.g. the 'terrain' color table can be assigned to the imported map with r.colors. See also their DEM portal.

Worldclim.org

To import Worldclim data, the following line has to be added to each .hdr file: 
PIXELTYPE SIGNEDINT

HDF

The import of HDF bands requires the specification of the individual bands as seen by GDAL: 
# Example MODIS FPAR
gdalinfo MOD15A2.A2003153.h18v04.004.2003171141042.hdf
...
Subdatasets:
  SUBDATASET_1_NAME=HDF4_EOS:EOS_GRID:"MOD15A2.A2003153.h18v04.004.2003171141042.hdf":MOD_Grid_MOD15A2:Fpar_1km
  SUBDATASET_1_DESC=[1200x1200] Fpar_1km MOD_Grid_MOD15A2 (8-bit unsigned integer)
  SUBDATASET_2_NAME=HDF4_EOS:EOS_GRID:"MOD15A2.A2003153.h18v04.004.2003171141042.hdf":MOD_Grid_MOD15A2:Lai_1km
  SUBDATASET_2_DESC=[1200x1200] Lai_1km MOD_Grid_MOD15A2 (8-bit unsigned integer)
...

# import of first band, here FPAR 1km:
r.in.gdal HDF4_EOS:EOS_GRID:"MOD15A2.A2003153.h18v04.004.2003171141042.hdf":MOD_Grid_MOD15A2:Fpar_1km \
          out=fpar_1km_2003_06_02
# ... likewise for other HDF bands in the file.

SEE ALSO

r.colors, r.in.ascii, r.in.arc, r.in.bin, r.null

GRASS GIS Wiki page: Import of Global datasets

REFERENCES

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

AUTHOR

Frank Warmerdam (email).

Last changed: $Date$