Commit 759d876e authored by Victor Poughon's avatar Victor Poughon

Merge branch 'cookbook-envvar' into 'develop'

Document third party environment variables

See merge request !124
parents e3739332 f60d7ea4
......@@ -11,11 +11,29 @@ that they only affect default values, and that settings in extended
filenames, applications, monteverdi or custom C++ code might override
those values.
* ``OTB_DEM_DIRECTORY``: Default directory were DEM tiles are stored. It should only contain ```.hgt`` or or georeferenced ``.tif`` files. Empty if not set (no directory set)
* ``OTB_GEOID_FILE``: Default path to the geoid file that will be used to retrieve height of DEM above ellipsoid. Empty if not set (no geoid set)
* ``OTB_MAX_RAM_HINT``: Default maximum memory that OTB should use for processing, in MB. If not set, default value is 128 MB.
* ``OTB_LOGGER_LEVEL``: Default level of logging for OTB. Should be one of ``DEBUG``, ``INFO``, ``WARNING``, ``CRITICAL`` or ``FATAL``, by increasing order of priority. Only messages with a higher priority than the level of logging will be displayed. If not set, default level is ``INFO``.
* ``OTB_DEM_DIRECTORY``: Default directory were DEM tiles are
stored. It should only contain ```.hgt`` or or georeferenced
``.tif`` files. Empty if not set (no directory set)
* ``OTB_GEOID_FILE``: Default path to the geoid file that will be used
to retrieve height of DEM above ellipsoid. Empty if not set (no
geoid set)
* ``OTB_MAX_RAM_HINT``: Default maximum memory that OTB should use for
processing, in MB. If not set, default value is 128 MB.
* ``OTB_LOGGER_LEVEL``: Default level of logging for OTB. Should be
one of ``DEBUG``, ``INFO``, ``WARNING``, ``CRITICAL`` or ``FATAL``,
by increasing order of priority. Only messages with a higher
priority than the level of logging will be displayed. If not set,
default level is ``INFO``.
In addition to OTB specific environment variables, the following
environment variable are parsed by third party libraries and also
affect how OTB works:
* ``GDAL_CACHEMAX``: Gdal has an internal cache mechanism to avoid reading or decoding again image chunks. This environnement variable controls how much memory Gdal can use for caching. By default, Gdal can use up to 5 percents of available RAM on system, which may be a lot. Moreover, caching is only needed if the processing chain is likely to request the same chunk several times, which is not likely to happen for a standard pixel based OTB pipeline. Setting a lower value allows to allocate more memory to OTB itself (using applications ``-ram`` parameter or ``OTB_MAX_RAM_HINT`` environment variable). If value is small (less than 100 000, it is assumed to be in megabytes, otherwise, it is assumed to be in bytes.
* ``GDAL_NUM_THREADS``: Gdal can take advantage of multi-threading to decode some formats. This variable controls the number of threads Gdal is allowed to use.
* ``OPJ_NUM_THREADS``: OpenJpeg can take advantage of mutli-threading when decoding images. This variable controls the number of threads OpenJpeg is allowed to use.
* ``ITK_GLOBAL_DEFAULT_NUMBER_OF_THREADS``: This variable allows to control the number of threads used by ITK for processing.
.. _extended-filenames:
Extended filenames
......
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