Issue 2.1
August 2001
|
MERIS IDL General Purpose Tools |
Issue 2.1 August 2001 |
Last modified: Thu Nov 29 18:34:02 2001.
NAME:
RD_RWMAP
PURPOSE:
retrieves data from MEGS L1 intermediate data files
and stores the content (header and optionaly data)
in a structure.
It accepts all types of MEGS L1b intermediate files:
tmp_rad1.meg, tmp_rad2.meg: calibrated & stray light corrected radiances resp.
tmp_fla1.meg, tmp_fla2.meg: pixel flags associated to above radiances resp.
tmp_buf.meg: geo-location and meteo annotations at tie points
tmp_pcd.meg: internal PCDs at both frame and product level
see OUTPUTS for more details on each file content
CATEGORY:
I/O
CALLING SEQUENCE:
map=RD_RWMAP(FILENAME=filename,/HEADER,/VERBOSE,/LAMBDA,/PIXEL, $
PARAM=param, ZONE=[X0,Y0,X1,Y1,DX,DY])
INPUTS:
All input parameters are passed with keywords (see below).
OPTIONAL INPUTS:
None
KEYWORD PARAMETERS:
FILENAME - data filename (need not be a MEGS file name, if not
the user will be asked for a type)
HEADER - when set only the header of the file is retrieved
DATA - when set only the data of the file is retrieved
VERBOSE - when set then produces additional diagnostic outputs
during the reading of the data file.
LAMBDA - when set then one field is created for each wavelength
(applicable to intermediate radiance files only:
tmp_rad1.meg or tmp_rad2.meg)
ZONE - integer array of 4,5 or 6 values defining area to retrieve
ZONE=[X0,Y0,X1,Y1,DX,DY] DX and DY are subsampling
factors in X/Y directions
PARAM - string array specifying the fields to retrieve
PIXEL - when set then annotations are interpolated to pixel product
OUTPUTS:
Structure with tags "header" and "data" the content of which vary
with the file type.
Note that data tag may be omitted if HEADER keyword is set.
1) radiance files:
"header" is a structure with tags :
filename - full path to the file (syntax is platform dependant)
common_hdr - file common header (for format identification only)
simulator_id - name of simulator that generated the file (MEGS or MERSS)
fld_03 - info field (software name and version, MEGS only)
fld_04 - info field (resolution in MEGS)
fld_05 - info field, not used
fld_06 - info field, not used
fld_07 - date array [yy,mm,dd,hh,mn,ss,ms] not used in MEGS
n_frames - number of frames in file (=AL dimension)
JD_first - UTC time of first frame (processing format)
JD_last - UTC time of last frame (processing format)
fld_11 - unused
fld_12 - index of first extracted module (starts at 1)
n_modules - number of extracted modules
n_columns - total number of columns (all modules, =AC dimension)
fld_15 - unused
n_bands - number of bands (=15)
wavelengths - array of band central wavelengths (nm)
band_widths - array of band widths (FWHM, nm)
"data" is a structure with tags :
l1masks - array of dimensions [n_columns,n_frames]
holding mask registers contained in file.
NOTE: those masks are not set within MEGS, they
are included for compatibility with MERSS format
and either a global array (default):
values - array of dimensions [n_bands,n_columns,n_frames] holding
radiance data for all bands
or per band arrays (optional keyword LAMBDA set):
rad1_xxx or rad2_xxx (depending on file type) - arrays of dimensions
[n_columns,n_frames] holding radiance data for
each band separately. xxx is the wavelength as extracted from
the header and rounded to nearest integer
2) flag files:
"header" is a structure with tags :
filename - full path to the file (syntax is platform dependant)
common_hdr - file common header (for format identification only)
n_frames - number of frames in file (=AL dimension)
n_columns - total number of columns (all modules, =AC dimension)
"data" is a structure with tags :
frame_index - vector of frame indices (length n_frames)
JD - vector of frame times in processing format (length n_frames)
valid_frame_f - vector of frame validity flags (1=valid, length n_frames)
l1saturated_f - array of saturated samples per band flags register, size [n_columns,n_frames]
l1dubious_f - array of dubious samples per band flags register, size [n_columns,n_frames]
l1cosmetic_f - array of cosmetic samples per band flags register, size [n_columns,n_frames]
Note: for the 3 per band flag registers above: flags for band b is coded on bit b
of given register (band and bit indices start at 0, bit 0 is least significant)
l1others_f - array of size [n_columns,n_frames] holding various per pixel flags,
bits meaning are (if set):
0:land, (not set means water, from Atlas only: no radiometry)
1:not used
2:coastline,
3:bright,
4:duplicate,
5:glint risk,
6:stray light risk,
7:invalid.
3) annotation file:
"header" is a structure with tags :
filename - full path to the file (syntax is platform dependant)
common_hdr - file common header (for format identification only)
n_tie_frames - number of Tie Frames in file (=AL dimension)
n_tie_columns - number of Tie Points (=AC dimension)
"data" is a structure with tags :
frame_index - vector of frame indices (length n_frames)
JD - vector of frame times in processing format (length n_frames)
pointing - array of pointing angles at Tie Points (TP), size [n_tie_columns,n_tie_frames]
latitude - array of latitudes at TP, size [n_tie_columns,n_tie_frames]
longitude - array of longitudes at TP, size [n_tie_columns,n_tie_frames]
altitude - array of altitudes at TP, size [n_tie_columns,n_tie_frames]
roughness - array of surface roughness at TP, size [n_tie_columns,n_tie_frames]
VAA - array of View Aziumth Angle at TP, size [n_tie_columns,n_tie_frames]
VZA - array of View Zenith Angle at TP, size [n_tie_columns,n_tie_frames]
SAA - array of Sun Aziumth Angle at TP, size [n_tie_columns,n_tie_frames]
SZA - array of Sun Zenith Angle at TP, size [n_tie_columns,n_tie_frames]
lat_corr - array of latitude correction at TP (due to altitude), size [n_tie_columns,n_tie_frames]
lon_corr - array of longitude correction at TP (due to altitude), size [n_tie_columns,n_tie_frames]
msl_press - array of mean sea level pressure at TP, size [n_tie_columns,n_tie_frames]
ozone - array of total column ozone at TP, size [n_tie_columns,n_tie_frames]
zonal_w - array of zonal wind at 10m height at TP, size [n_tie_columns,n_tie_frames]
merid_w - array of meridional wind at 10m height at TP, size [n_tie_columns,n_tie_frames]
humidity - array of relative humidity at TP, size [n_tie_columns,n_tie_frames]
4) PCD file:
"header" is a structure with tags :
filename - full path to the file (syntax is platform dependant)
common_hdr - file common header (for format identification only)
n_frames - number of frames in file (=AL dimension)
n_modules - number of modules in file (=AC dimension)
"data" is a structure with tags :
frame_index - vector of frame indices (length n_frames)
JD - vector of frame times in processing format (length n_frames)
OutRgPCD - array of image pixels Out Of Range PCD, size [16,n_modules,n_frames]
BlankPCD - array of Blank Pixels PCD, size [16,n_modules,n_frames]
TRANS_ERR - Transmission Error PCD (product wide, scalar)
FORMAT_ERR - Format Error PCD (product wide, scalar)
COARSE_ERR - Coarse Offsets Error PCD (product wide, scalar)
DATABASE_ERR - Auxiliary Database Error PCD (product wide, scalar)
ECMWF_TYPE - ECMWF Data Type PCD (product wide, scalar)
ECMWF_LAG - ECMWF Validity Time PCD (product wide, scalar)
OPTIONAL OUTPUTS:
When HEADER keyword is set then only the header is retrieved
from the rwmap data file and the "DATA" tag is not present in
the structure that is retrieved with this function.
COMMON BLOCKS:
None
SIDE EFFECTS:
Unknown
RESTRICTIONS:
None
PROCEDURE:
If filename is not passed as argument, a file browser is submitted to the user,
when the filename is retrieved, either its type is recognised from the name or
it is requested from the user. File is then checked for existence, readability and
format. If everything is OK, the file is read record after record, each header
and data tag is dimensioned according to its own record ID and header sizing
parameters. Some field dimension and content are checked to confirm that the
file is of rwmap format.
EXAMPLES:
struct=rd_rwmap()
FILENAME='/megs/megs.4.3/folders/sat_l1/RR_Geoloc/files/tmp_rad1.meg'
struct=RD_RWMAP(FILENAME=filename,/HEADER,/VERBOSE)
struct=RD_RWMAP(FILENAME=filename,/VERBOSE)
struct=RD_RWMAP(FILENAME=filename)
struct=RD_RWMAP(FILENAME=filename,/LAMBDA)
filename='/megs_test/validation/Level1b/Perfo/limub_pacific_45_stray.mer_RR'
struct=rd_rwmap(FILENAME=filename)
MODIFICATION HISTORY:
Created Friday February 18 2000 by Vincent Fournier-Sicre - vfs@acri.fr
modified 22/11/00 by lb@acri.fr (added read of 'tmp_buf.meg', L1B annotations
intermediate file, see rd_rwmap_data)
modified 03/12/00 by lb@acri.fr (replaced str_sep by strsplit)
modified 20/11/01 by lb@acri.fr (added read of 'tmp_fla?.meg', 'tmp_pcd.meg',
L1B flags and PCDs intermediate files, see rd_rwmap_data)
modified 20/11/01 by lb@acri.fr: uniformisation of interfaces, documentation update,
new keywords.
(See $IDL_LOCAL\Meris\rd_rwmap.pro)