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[McIDAS #SSN-755786]: Meteosat question



Hi Bernie,

Sorry for the delay in replying.  Recovering from my trip took longer
than usual :-(

re:
> A binary file with a separate lat/lon file should work if I know how
> the files are written.  This would probably be the best format.

OK.  The McIDAS application you need to investigate is AXFORM.  The
output format of the files as explained by the online HELP is
very simple:

<in a McIDAS session>
HELP AXFORM

AXFORM - Converts a McIDAS Area file to ASCII or binary flat files
   AXFORM sarea file <keywords>
Parameters:
   sarea | digital area number
   file | output file; maximum of 100 characters; specify as a file name
          or a fully qualified path (directory and file name); do not
          include an extension with the file name; see the Remarks
Keywords:
   BANd=    | band numbers for a multibanded sarea (def=first band)
       =ALL | all bands of sarea
   FLIp=YES | flip bytes; specify this keyword when the byte order on the
              destination system is the reverse of the source system,
              e.g., from a PC to a Unix workstation (def=NO)
   FORmat=I1 | output elements are 1 byte integers
         =I2 | output elements are 2 byte integers
         =I4 | output elements are 4 byte integers
   FTYpe=BIN  | binary files (as specified in FORMAT keyword) (def)
        =ASC  | ASCII text files (w/ 25I10 format)
        =BOTH | both file types
   MISs= | missing data value for .LAT/.LON extension files
           (def=65535 Hex FFFF)
   NAV=YES inc | produce .LAT/.LON data files with an element
                 increment; these files contain LAT/LON stored as
                 degrees*100 (2 bytes per element); the increment is the
                 the number of data elements associated with each LAT/LON
                 element (def=NO 1)
   UNIt=    | calibration units of output files (def=cal units of sarea)
       =ALL | all calibration units defined by sarea
Remarks:
   AXFORM creates a set of files which contain data from sarea. These
   files maybe ported to other non-McIDAS systems. Data is represented
   as 2 dimensional arrays of binary or ASCII fields whose dimensions
   are those of the original sarea lines/elements.

   An ASCII output text file documents the format of the output data files.
   It contains a listing for each of the data files generated. Output files
   are assigned unique extensions:
     .HDR (header file) - This file contains ASCII text describing sarea
                          and the contents of the output data files.
     .nnn (data files) - These files contain binary data for a single
                         calibration of a specific band.
                         (nnn ranges from 001 to 999)
     .Ann (data files) - These files contain ASCII data for a single
                         calibration of a specific band.
                         (nn ranges from 01 to 99)
     .LAT (latitude file) - If NAV=YES, binary file contains a 2
                            dimensional array of latitudes corresponding
                            to the elements within the output data files.
     .LON (longitude file) - If NAV=YES, binary file contains a 2
                             dimensional array of longitudes corresponding
                             to the elements within the output data files.
     .ALT (latitude file) - If NAV=YES, ASCII file contains a 2
                            dimensional array of latitudes corresponding
                            to the elements within the output data files.
     .ALN (longitude file) - If NAV=YES, ASCII file contains a 2
                             dimensional array of longitudes corresponding
                             to the elements within the output data files.

   Defaults for the FORMAT keyword (assume FTYPE=BIN or BOTH):
     if: UNIT=BRIT   then: FORMAT=I1 (1 byte integer)
              TEMP                I2 (2 byte integer)
              RAD/RADN            I4 (4 byte integer)
              ALB                 I2 (2 byte integer)
              REF/RERA            I2 (2 byte integer)
              CNTS                I2 (2 byte integer)
              RAW                  #bytes/element from sarea directory
              other               I1 (1 byte integer)
   FORMATs smaller than the default size are NOT allowed.

As you can see, you can output the data in binary or ASCII format.  I
assume you will want binary since an ASCII dump of a full image will
be HUGE.

re:
> Also hdf5 files are OK.  I also have an IDL netcdf file reader that I can
> use.

Sorry, McIDAS has no built-in capability to write to HDF5 files.

By the way, I got a note from a friend in SSEC who is converting a different
kind of image (the national 1 km composite base reflectivity radar product
we make available by LDM/IDD transfer); remapping it to a rectilinear
(Lat,Lon) projection; saving it in a GeoTIFF file (I mentioned this capability
earlier); and making that image available through a web map service.  You
can see the results in:

http://dcdbs.ssec.wisc.edu:8080/nexrcomp.html

I mention this since I have a hunch that IDL might just support GeoTIFF.

Cheers,

Tom
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Ticket Details
===================
Ticket ID: SSN-755786
Department: Support McIDAS
Priority: Normal
Status: Closed


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