gdalinfo

This utility allows to get several info from the GDAL library, for instance, specific Driver capabilities and input Datasets/Files properties.

gdalinfo --format GTIFF

Format Details:
  Short Name: GTiff
  Long Name: GeoTIFF
  Extension: tif
  Mime Type: image/tiff
  Help Topic: frmt_gtiff.html
  Supports: Create() - Create writeable dataset.
  Supports: CreateCopy() - Create dataset by copying another.
  Supports: Virtual IO - eg. /vsimem/
  Creation Datatypes: Byte UInt16 Int16 UInt32 Int32 Float32 Float64 CInt16 CInt32 CFloat32 CFloat64
  <CreationOptionList>
  <Option name="COMPRESS" type="string-select">
         <Value>NONE</Value>
         <Value>LZW</Value>
         <Value>PACKBITS</Value>
         <Value>JPEG</Value>
         <Value>CCITTRLE</Value>
         <Value>CCITTFAX3</Value>
         <Value>CCITTFAX4</Value>
         <Value>DEFLATE</Value>
  </Option>
  <Option name="PREDICTOR" type="int" description="Predictor Type" />
  <Option name="JPEG_QUALITY" type="int" description="JPEG quality 1-100" default="75"/>
  <Option name="ZLEVEL" type="int" description="DEFLATE compression level 1-9" default="6" />
  <Option name="LZMA_PRESET" type="int" description="LZMA compression level 0(fast)-9(slow)" default="6" />
  <Option name="NBITS" type="int" description="BITS for sub-byte files (1-7), sub-uint16 (9-15), sub-uint32 (17-31)" />
  <Option name="INTERLEAVE" type="string-select" default="PIXEL">
         <Value>BAND</Value>
         <Value>PIXEL</Value>
  </Option>
  <Option name="TILED" type="boolean" description="Switch to tiled format"/>
  <Option name="TFW" type="boolean" description="Write out world file"/>
  <Option name="RPB" type="boolean" description="Write out .RPB (RPC) file" />
  <Option name="BLOCKXSIZE" type="int" description="Tile Width"/>
  <Option name="BLOCKYSIZE" type="int" description="Tile/Strip Height"/>
  <Option name="PHOTOMETRIC" type="string-select">
         <Value>MINISBLACK</Value>
         <Value>MINISWHITE</Value>
         <Value>PALETTE</Value>
         <Value>RGB</Value>
         <Value>CMYK</Value>
         <Value>YCBCR</Value>
         <Value>CIELAB</Value>
         <Value>ICCLAB</Value>
         <Value>ITULAB</Value>
  </Option>
  <Option name="SPARSE_OK" type="boolean" description="Can newly created files have missing blocks?" default="FALSE" />
  <Option name="ALPHA" type="boolean" description="Mark first extrasample as being alpha" />
  <Option name="PROFILE" type="string-select" default="GDALGeoTIFF">
         <Value>GDALGeoTIFF</Value>
         <Value>GeoTIFF</Value>
         <Value>BASELINE</Value>
  </Option>
  <Option name="PIXELTYPE" type="string-select">
         <Value>DEFAULT</Value>
         <Value>SIGNEDBYTE</Value>
  </Option>
  <Option name="BIGTIFF" type="string-select" description="Force creation of BigTIFF file">
         <Value>YES</Value>
         <Value>NO</Value>
         <Value>IF_NEEDED</Value>
         <Value>IF_SAFER</Value>
  </Option>
  <Option name="ENDIANNESS" type="string-select" default="NATIVE" description="Force endianness of created file. For DEBUG purpose mostly">
         <Value>NATIVE</Value>
         <Value>INVERTED</Value>
         <Value>LITTLE</Value>
         <Value>BIG</Value>
  </Option>
  <Option name="COPY_SRC_OVERVIEWS" type="boolean" default="NO" description="Force copy of overviews of source dataset (CreateCopy())" />
  </CreationOptionList>

gdal_translate

This utility allows to convert a dataset to a different format by allowing a wide set of parameters to customize the conversion.

Running the command:

gdal_translate

allows to get the list of supported parameters as well as the supported output formats:

Usage: gdal_translate [--help-general]
       [-ot {Byte/Int16/UInt16/UInt32/Int32/Float32/Float64/
             CInt16/CInt32/CFloat32/CFloat64}] [-strict]
       [-of format] [-b band] [-mask band] [-expand {gray|rgb|rgba}]
       [-outsize xsize[%] ysize[%]]
       [- unscale] [-scale [src_min src_max [dst_min dst_max]]]
       [-srcwin xoff yoff xsize ysize] [-projwin ulx uly lrx lry]
       [-a_srs srs_def] [-a_ullr ulx uly lrx lry] [-a_nodata value]
       [-gcp pixel line easting northing [elevation]]*
       [-mo "META-TAG=VALUE"]* [-q] [-sds]
       [-co "NAME=VALUE"]* [-stats]
       src_dataset dst_dataset

Where the meaning of the main parameters is summarized below:

• -ot: allows to specify the output datatype (Make sure that the specified datatype is contained in the Creation Datatypes list of the Writing driver)
• -of: specify the desired output format (GTIFF is the default value)
• -b: allows to specify an input band to be written in the output file. (Use multiple -b option to specify more bands)
• -mask: allows to specify an input band to be write an output dataset mask band.
• -expand: allows to expose a dataset with 1 band with a color table as a dataset with 3 (rgb) or 4 (rgba) bands. The (gray) value allows to expand a dataset with a color table containing only gray levels to a gray indexed dataset.
• -outsize: allows to set the size of the output file in terms of pixels and lines unless the %sign is attached in which case it’s as a fraction of the input image size.
• -unscale: allows to apply the scale/offset metadata for the bands to convert from scaled values to unscaled ones.
• -scale: allows to rescale the input pixels values from the range src_min to src_max to the range dst_min to dst_max. (If omitted the output range is 0 to 255. If omitted the input range is automatically computed from the source data).
• -srcwin: allows to select a subwindow from the source image in terms of xoffset, yoffset, width and height
• -projwin: allows to select a subwindow from the source image by specifying the corners given in georeferenced coordinates.
• -a_srs: allows to override the projection for the output file. The srs_def may be any of the usual GDAL/OGR forms, complete WKT, PROJ.4, EPSG:n or a file containing the WKT.
• -a_ullr: allows to assign/override the georeferenced bounds of the output file.
• -a_nodata: allows to assign a specified nodata value to output bands.
• -co: allows to set a creation option in the form “NAME=VALUE” to the output format driver. (Multiple -co options may be listed.)
• -stats: allows to get statistics (min, max, mean, stdDev) for each band
• src_dataset: is the source dataset name. It can be either file name, URL of data source or subdataset name for multi*-dataset files.
• dst_dataset: is the destination file name.

gdaladdo

This utility allows to add overviews to a dataset. The following steps provide instructions to add overviews to the tiled sample dataset.

Running the command:

gdaladdo

allows to get the list of supported parameters:

Usage: gdaladdo [-r {nearest,average,gauss,average_mp,average_magphase,mode}]
                [-ro] [--help-general] filename levels

Where the meaning of the main parameters is summarized below:

• -r: allows to specify the resampling algorithm (Nearest is the default value)
• -ro: allows to open the dataset in read-only mode, in order to generate external overview (for GeoTIFF especially)
• filename: represents the file to build overviews for.
• levels: allows to specify a list of overview levels to build.

Process in bulk

Instead of manually repeating these 2 steps (retile + add overviews) for each file, we can invoke a few commands to get it automated.

1. Run:

• Linux:

  cd ${TRAINING_ROOT}/data/user_data
  
  mkdir optimized
  
  cd aerial
  
  for i in `find *.tif`; do gdal_translate -CO "TILED=YES" -CO "BLOCKXSIZE=512" -CO "BLOCKYSIZE=512" $i ../optimized/$i; gdaladdo -r average ../optimized/$i 2 4 8 16 32; done
  

• Windows:

  cd %TRAINING_ROOT%\data\user_data\
  
  mkdir optimized
  
  cd aerial
  
      notepad optimize.bat
  

  will be open a text editor. Copy the following content:

  for %%F in (*.tif) do  (
        echo Processing file %%F
  
        REM translate
        echo Performing gdal_translate on file %%F to file %%~nF.tiff
        gdal_translate -co "TILED=YES" -co "BLOCKXSIZE=512" -co "BLOCKYSIZE=512" -co "COMPRESS=DEFLATE" %%F ..\optimized\%%~nF.tiff
  
        REM add overviews
        echo Adding overviews on file %%~nF.tiff
        gdaladdo -r average --config COMPRESS_OVERVIEW DEFLATE ..\optimized\%%~nF.tiff 2 4 8 16 32
  
  )
  

  Then save the file and run the created .bat file:

  optimize.bat
  

1. You should see a list of run like this:

   ...
   Input file size is 2500, 2500
   0...10...20...30...40...50...60...70...80...90...100 - done.
   0...10...20...30...40...50...60...70...80...90...100 - done.
   Input file size is 2500, 2500
   0...10...20...30...40...50...60...70...80...90...100 - done.
   0...10...20...30...40...50...60...70...80...90...100 - done.
   Input file size is 2500, 2500
   0...10...20...30...40...50...60...70...80...90...100 - done.
   0...10...20...30...40...50...60...70...80...90...100 - done.
   ...
   

At this point optimized datasets have been prepared and they are ready to be served by GeoServer as an ImageMosaic.

gdalwarp

This utility allows to warp and reproject a dataset. The following steps provide instructions to reproject the aerial dataset (which has “EPSG:26913” coordinate reference system) to WGS84 (“EPSG:4326”).

Running the command:

gdalwarp

allows to get the list of supported parameters:

Usage: gdalwarp [--help-general] [--formats]
       [-s_srs srs_def] [-t_srs srs_def] [-to "NAME=VALUE"]
       [-order n | -tps | -rpc | -geoloc] [-et err_threshold]
       [-refine_gcps tolerance [minimum_gcps]]
       [-te xmin ymin xmax ymax] [-tr xres yres] [-tap] [-ts width height]
       [-wo "NAME=VALUE"] [-ot Byte/Int16/...] [-wt Byte/Int16]
       [-srcnodata "value [value...]"] [-dstnodata "value [value...]"] -dstalpha
       [-r resampling_method] [-wm memory_in_mb] [-multi] [-q]
       [-cutline datasource] [-cl layer] [-cwhere expression]
       [-csql statement] [-cblend dist_in_pixels] [-crop_to_cutline]
       [-of format] [-co "NAME=VALUE"]* [-overwrite]
       srcfile* dstfile

Where the meaning of the main parameters is summarized below:

• -s_srs: allows to specify the source coordinate reference system
• -t_srs: allows to specify the target coordinate reference system
• -te: allows to set georeferenced extents (expressed in target CRS) of the output
• -tr: allows to specify the output resolution (expressed in target georeferenced units)
• -ts: allows to specify the output size in pixel and lines.
• -r: allows to specify the resampling method (one of near, bilinear, cubic, cubicspline and lanczos)
• -srcnodata: allows to specify band values to be excluded from interpolation.
• -dstnodata: allows to specify nodata values on output file.
• -wm: allows to specify the amount of memory (expressed in megabytes) used by the warping API for caching.