=encoding utf8

=head1 NAME

Geo::Format::Envisat - parse Envisat metadata format

=head1 INHERITANCE

 Geo::Format::Envisat
   is a Exporter

=head1 SYNOPSIS

 use Geo::Format::Envisat;

 # base info solely on filename (fast!)
 my $mph  = envisat_mph_from_name $filename;

 # collect all meta-data from inside the file
 my $meta = envisat_meta_from_file $filename;

 use Data::Dumper;
 print Dumper $meta;   # see the returned structure

 # see examples/ directory!!

=head1 DESCRIPTION

Simply transform the meta-data which leads Envisat and ERS imagery
into Perl HASHes for easy access.  All keys which are upper-case
follow the official document.  Lower-cased fields are added for each
of the official names, which are preprocessed to simplify further
processing, like translation of time fields to OS time values and an
iso representation.  The lower-cased key names will also have blanks
stripped from the end and abbreviated codes extended for readability.

The formats are described in various documents available from
F<http://earth.esa.int/pub/ESA_DOC/ENVISAT/>

Used are C<Vol05_Structures_3d_20071122.pdf> (Main Product Header
description version 2007-11-22) and C<Vol08_Asar_4B_20071025.pdf>
(ASAR file format specifics version 2007-10-25).

=head1 FUNCTIONS

=over 4

=item B<envisat_meta_from_file>(FILENAME, OPTIONS)

Read all meta-data from the file specified by its FILENAME.  The file
can be in compressed form, although you may need to install some
additional C<IO::Uncompress> modules.

 -Option          --Default
  take_dsd_content  <false>

=over 2

=item take_dsd_content => BOOLEAN

Collect the content from all non-measurement DSD records.  These are
binary fields.

=back

example: envisat_meta_from_file

 my $meta = envisat_meta_from_file $fn;
 my $mph = $meta->{mph};  # Main Product Header
 my $sph = $meta->{sph};  # Specific Product Header
 my $mds = $meta->{dsd}{MSD1};  # data-set description

=item B<envisat_mph_from_name>(FILENAME|STRING)

Pass the product FILENAME as STRING, and it will get decomposed into
some records which are also in the Main Product Header meta-data records.
This permits some easy searching in directories without the need to open
the (sometimes compressed, always large) files.

Compression extensions at the end of the STRING will be ignored.  The
name will be upper-cased before processing.  Undef is returned when
there is no match.  Some information can be added if the STRING actually
refers to an existing FILENAME.  Therefore, you may pass a filename
which contains directory components.

example: envisat_mph_from_name

 my $fn  = 'ASA_IMG_1PNDPA20080903_100725_000000152071_00423_34044_1202.N1';
 my $mph = envisat_mph_from_name $fn;

=back

=head1 SEE ALSO

This module is part of Geo-Format-Envisat distribution version 0.90,
built on January 23, 2018. Website: F<http://perl.overmeer.net/CPAN/>

=head1 LICENSE

Copyrights 2008-2018 by [Mark Overmeer]. For other contributors see ChangeLog.

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
See F<http://dev.perl.org/licenses/>

