Processing MODIS data with MODISL1DB will result in
identical products to those produced by the OBPG if the same calibration
LUTs are used, as outlined in the SeaDAS Processing Version Chart.
IMPORTANT: MODISL1DB version 1.5 contains no processing code
changes, but many of the Unix binaries have been renamed for
standardization purposes (and to stay in sync with SeaDAS). This will
NOT affect most users, since the wrapper processing scripts have not
been renamed and these scripts are all that is needed to carry out
the processing. Also note that some new platforms are supported, and all Linux
processing binaries are now statically linked which may allow users to
run MODISL1DB on a wider variety of unsupported Linux systems. See the
version history for more details.
Please be aware that if the SeaDAS software package is already installed
on your computer, you will already have full access to ALL of the
functionality of MODISL1DB. If you do decide to also install MODISL1DB,
SeaDAS and MODISL1DB should NOT both be enabled at the same time. To
disable SeaDAS, simply comment-out any lines in your shell initialization
file that set up the SeaDAS environment.
MODISL1DB can be downloaded and installed using the
online
installation page. The online installer will do everything for you,
including downloading files, installing the software, and setting up your
UNIX environment for MODISL1DB. Or, you can
manually download
MODISL1DB, and follow the installation instructions.
Using MODISL1DB
MODISL1DB is command-line driven, with processing controlled by four main
wrapper scripts: modis_L0_to_L1A_GEO.csh,
modis_L1A_extract.csh,
modis_L1A_to_GEO.csh, and modis_L1A_to_L1B.csh.
Two utility scripts (modis_update_luts.csh and
modis_update_utcpole_leapsec.csh) are also included to automate updating
of calibration LUTs and utcpole.dat/leapsec.dat. It is suggested these two
scripts be set up as cron jobs, though they can also be run manually. All
MODISL1DB scripts reside in the top-level 'scripts' directory. For usage
instructions please consult each script's associated README file:
The $DBHOME/scripts/modisl1db_benchmarks.bash script will
process a user-specified Level 0 PDS file to L1A/GEO and then to
L1B, calculating the time required for processing. The
MODISL1DB BENCHMARKS TABLE
lists processing times from various platforms for processing the
specific Aqua L0 file
MOD00.P2006214.0540_1.PDS (260MB).
This table can be used for comparing your local computer's performance to
other platforms. If you perform benchmarks using the standard file,
please email results to
seadas@seadas.gsfc.nasa.gov
for inclusion in the table.
Source Code
Source code is not distributed with the MODISL1DB software package.
However, the complete source code and build environment for all MODISL1DB
binaries is available within the
SeaWiFS
Data Analysis System (SeaDAS) software package.
To build custom MODISL1DB binaries, users can install SeaDAS and then
rebuild any of the MODISL1DB binaries within their SeaDAS environment.
These custom binaries can then be substituted directly into an existing
MODISL1DB installation. Or, if the processing component of SeaDAS is
installed (distributed in the file seadas_processing.tar.gz), the
following SeaDAS script can be run to create a complete MODISL1DB package
(created in $SEADAS/modisl1db/) containing the new custom binaries:
