KEA

Starting with GDAL 2.0, GDAL can read, create and update files in the KEA format, through the libkea library.

KEA is an image file format, named after the New Zealand bird, that provides a full implementation of the GDAL data model and is implemented within a HDF5 file. A software library, likea, is used to access the file format. The format has comparable performance with existing formats while producing smaller file sizes and is already within active use for a number of projects within Landcare Research, New Zealand, and the wider community.

The KEA format supports the following features of the GDAL data model:

• Multiple-band support, with possible different datatypes. Bands can be added to an existing dataset with AddBand() API
• Image blocking support
• Reading, creation and update of data of image blocks
• Affine geotransform, WKT projection, GCP
• Metadata at dataset and band level
• Per-band description
• Per-band nodata and color interpretation
• Per-band color table
• Per-band RAT (Raster Attribute Table) of arbitrary size
• Internal overviews and mask bands

Creation options

The following creation options are available. Some are rather esoteric and should rarely be specified, unless the user has good knowledge of the working of the underlying HDF5 format.

• IMAGEBLOCKSIZE=integer_value: The size of each block for image data. Defaults to 256

• ATTBLOCKSIZE=integer_value: The size of each block for attribute data. Defaults to 1000

• MDC_NELMTS=integer_value: Number of elements in the meta data cache. Defaults to 0. See the Data caching page of HDF5 documentation.

• RDCC_NELMTS=integer_value: Number of elements in the raw data chunk cache. Defaults to 512. See the Data caching page of HDF5 documentation.

• RDCC_NBYTES=integer_value: Total size of the raw data chunk cache, in bytes. Defaults to 1048576. See the Data caching page of HDF5 documentation.

• RDCC_W0=floating_point_value between 0 and 1: Preemption policy. Defaults to 0.75. See the Data caching page of HDF5 documentation.

• SIEVE_BUF=integer_value: Sets the maximum size of the data sieve buffer. Defaults to 65536. See H5Pset_sieve_buf_size() documentation

• META_BLOCKSIZE=integer_value: Sets the minimum size of metadata block allocations. Defaults to 2048. See H5Pset_meta_block_size() documentation

• DEFLATE=integer_value: Compression level between 0 (no compression) to 9 (max compression). Defaults to 1

• THEMATIC=YES/NO: If YES then all bands are set to thematic. Defaults to NO

See Also:

• libkea bitbucket repository
• The KEAimage file format, by Peter Bunting and Sam Gillingham, published in Computers&Geosciences
• HDF5 driver page