MIGARS -- GARS Tape to Database Transfer

Transfers image data from any GARS format magnetic tape to an image database file.

Progress of this program can be monitored. See MONITOR section.

Warning: The program wasn't tested for 16-bits multi-band tapes.

PARAMETERS

MIGARS is controlled by the following global parameters: 

Name     Prompt                                  Count     Type
FILE     Database File Name                      1-64      Char
MTIC     Mag Tape Input Channel List             1-13      Int
DBOC     Database Output Channel List            1-13      Int
MTIW     Mag Tape Input Window                   0-4       Int
DBOW     Database Output Window                  0-4       Int
STARTFIL Start File on Tape                      1         Int

FILE

Specifies the PCIDSK file to write imagery data to: 

 EASI>FILE="file specification"

MTIC

The PACE parameter MTIC represents a list of image channels that reside on the input magnetic tape: 

 EASI>MTIC=i,j,...,m

DBOC

The PACE parameter DBOC represents a list of output image channels that reside on a database image file: 

 EASI>DBOC=i,j,...,m

MTIW

The PACE parameter MTIW represents a window on the magnetic tape to be transferred to the image database file: 

 EASI>MTIW=Xoffset,Yoffset,Xsize,Ysize
 EASI>MTIW=                     | defaults to entire image

DBOW

The PACE parameter DBOW represents a window on the image database, where data will be transferred from magnetic tape: 

 EASI>DBOW=Xoffset,Yoffset,Xsize,Ysize
 EASI>DBOW=                     | defaults to enire image database

STARTFIL

Specifies the start file number on tape from which to start reading header and image data. If STARTFIL is greater than one, the program rewinds the tape and advances to the specified file. STARTFIL must be set to the file number required by MSH program to print tape header report. 

 EASI>STARTFIL=1              | read first file on tape
 EASI>STARTFIL=n              | read nth file on tape

DETAILS

MIGARS (GEOS Archive and Retrieval System Format) transfers image data from any set of bands (up to 13 bands for VAS) on GEOS tape (MTIC) to any set of image channels on an existing PCI database file (DBOC). Normally, an empty database file is created using CIM before running MIGARS.

Any arbitrary rectangular window on tape (MTIW) can be transferred to any arbitrary rectangular window on the database (DBOW). Shrinking and/or zooming is automatically performed. By default, the whole tape image is transferred, filling the entire database. 

 A TAPE MUST BE MOUNTED ON THE TAPE DRIVE BEFORE MIGARS CAN BE RUN.
 CLEANING THE TAPE HEADS IS RECOMMENDED TO MINIMIZE THE CHANCE
 OF TAPE READ ERRORS.

MONITOR

Program progress can be monitored by printing the percentage of completed processing in odometer fashion. A system parameter, MONITOR, controls this activity: 

 EASI>MONITOR="ON"           | turn monitor ON  (default)
 EASI>MONITOR="OFF"          | turn monitor OFF (recommended if
                             | running in batch/background mode)

GARS TAPE FORMAT

A GARS Format tape will contain one or several set of data followed by an end_of_file mark. A second end_of_file mark will be written after the last file on each tape.

Each data set will contain one GOES sector (file), either a VISSR or a VAS sector (file). Each Physical Record is of fixed length, 7704 bytes. The first 24 bytes of physical record contain a header, and the remaining 7680 bytes contain data (or may be empty or partially empty, depending on the record type.) The physical record header allows the physical records to be self identifying, in that each physical record header contains information describing its record type and its position within the data set as a whole.

VISSR or VAS sector (file) consists of a series of WEST-EAST lines in sequential order from NORTH to SOUTH covering a specified geographical area. Each line is a series of pixels in WEST to EAST order. Each pixel will be either an unsigned 8 bit integer for a VISSR file (representing a visible or IR data for that earth location)or a set of from one to twelve signed 16-bits integers for VAS sector (representing data values from a set of one to twelve different spectral bands for that earth location).

Each line within the file (sector) is written as a logical record consisting of a line prefix followed by a series of pixels making up the line.

All of the line within a file contain the same number of pixel and are thus all of the same length, as are the line prefix. The logical record length within the file is fixed.

Logical record are pack in physical record.

Each physical record will contain a physical record header followed by one or more logical records. Logical record may cross physical record boundaries, so physical record may begin and/or end with fractional logical records.

There nine types of logical records. Only one type of logical record will be contained in any given physical record. A VISSR or VAS files will always begins and end with the Header and End logical records respectively, other types will fall between. Types of logical record; Label, Comment, Header, Directory (contain information about size of the file),Navigation, Chebyshev Navigation, Auxiliary, Data (contain image data) and END.

EXAMPLE

Before running MIGARS, check header information by MSH program: Read the volume descriptor for the first image file. 

 EASI>MTSH=
 EASI>STARTFIL=1
 EASI>R MSH

  MSH     Mag Tape Source Header Listing  V5.1  13:13 09-Sep-92

  GARS Format Scene Header

  Date (YYDDD)              >    80282
  Satellite                 :   SMS-2 
  First line coordinate     >       33
  First pixel coordinate    >        1
  Pixels per scanline       >    15200
  Scanlines per image       >     6818
  Number of bits per pixel  >        8
  Number of band on tape    >        1
  Logical record (bytes)    >    15204
  Prefix line length (bytes)>        4
  List of band on tape      >        1
Use CIM program to create PCI database. 

 EASI>FILE="Meteo.pix"            | File name
 EASI>TEX1="GARS Image"           | Descriptive text
 EASI>TEX2=
 EASI>DBSZ=15200,6818             | 512 pixels by 512 lines
 EASI>DBNC=1                      | 1 8-bit channel
 EASI>DBLAYOUT="PIXEL"            | pixel interleaving
 EASI>RUN CIM
STARTFIL as is and run MIGARS. Transfer file of the magnetic tape channels 1 to channels 1 in database file METEO.PIX. 

 EASI>FILE="METEO.PIX"
 EASI>MTIC=1
 EASI>DBOC=1
 EASI>MTIW=
 EASI>DBOW=
 EASI>RUN MIGARS
After running the program following message appear: 

 Invalid lines, not transferred to database:  20
It means that 20 lines were invalid on the tape (from 6818) and last 20 lines on PCI database will not contain image data.

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