MSPOT -- Magtape SPOTIMAGE SPOT Format

Reads SPOT imagery from a SPOTIMAGE LGSOWG format tape, when satellite orthorectification is required. MSPOT automatically creates a PCIDSK file, reads all of the requested imagery @@channels@@ from tape, and saves the satellite path information in one or two @@segments@@.

The output file from MSPOT is used as input to the programs SMODEL and SORTHO.

Note: The MIL program can also be used to read LGSOWG format tapes in a more general way; however, output from MIL cannot be used for orthorectification.

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

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PARAMETERS

MSPOT is controlled by the following global parameters:

Name     Prompt                                  Count     Type
FILE     Database File Name                      1-64      Char
MTIC     Mag Tape Input Channel list             1-16      Int
TEX1     Database Descriptive Text 1             0-64      Char
REPORT   Report Mode: TERM/OFF/filename          1-64      Char

The following parameters receive output:

ORBIT    Orbit Segment                           1         Int

FILE

Specifies the name of the PCIDSK file to receive data. This file will be created automatically and must not already exist.

 EASI>FILE="filespec"

MTIC

Specifies the list of channels to read from the tape. For each channel specified, a channel will be created on the PCIDSK file (FILE).

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

Ranges of channels can be specified with negative values. For example: {1,-4,10} is internally expanded to {1,2,3,4,10}. There is 1 channel on a SPOT panchromatic tape and there are 3 channels on a SPOT multispectral tape. SPOT panchromatic requires about 40 Mbytes of disk space and SPOT multispectral requires about 10 Mbytes of disk space (30 Mbytes for all 3 channels). This amount of space must be available before MSPOT is run.

TEX1

Optionally specifies a line of text describing the file. Typically this would contain information identifying the location of the data and the tape reference number.

 EASI>TEX1="string"

REPORT

Specifies where the tape information report should be directed. This report contains tape header and orbital information.

 EASI>REPORT="filename"
 EASI>REPORT=            | defaults to terminal output

Note: The following names have special meaning:

 EASI>REPORT="TERM"     | generates reports on your terminal
 EASI>REPORT="DISK"     | generates reports on file "IMPRPT.LST"
 EASI>REPORT="OFF"      | usually cancels report generation, but
                        | MSPOT forces REPORT to terminal output

ORBIT

This parameter receives the number of the segment in which the orbital information was saved.

DETAILS

The MSPOT program is part of the satellite orthorectification package. It is used to read SPOT imagery from a SPOTIMAGE LGSOWG format tape, when satellite orthorectification is required. MSPOT automatically creates a PCIDSK file, reads all of the requested imagery channels from tape, and saves the satellite path information in one or two segments. Output from MSPOT is used with the SMODEL and SORTHO programs.

The SPOTIMAGE LGSOWG tape makes available different levels of processing. This program supports level 0, 1A and 1B tapes. However, level 1A is always recommended for highest accuracy. The user should always use 1A data if possible. MSPOT supports both old SPOTIMAGE LGSOWG and the new CAP-T format.

The MSPOT program will extract from the tape the geographic coordinates of the scene centre and the 4 corner points, and the corresponding pixel and line positions. The values are stored in the ORBIT segment. These points can be used as GCPs input to the SMODEL program for an approximate correction. It is useful for the case where the user cannot obtain any GCPs for an area. Since the geographic coordinates are not very accurate, the user should not expect very accurate results if those points are used. Also, the 4 corner points should not be used to generate DEM from stereo pair.

The FILE parameter is used to specify the name of the PCIDSK file to hold the imagery and orbital information read off tape. This file is automatically created with the dimensions required to hold all of the requested data. The user should ensure that sufficient disk space is available before MSPOT is run. Typically this is about 10 Mbytes per specified channel for SPOT multispectral, and about 40 Mbytes for SPOT panchromatic.

Note: Typically there are 3 channels on a SPOT multispectral tape and 1 channel on a SPOT panchromatic tape. The MSH program can be run to check the number of channels on tape.

The ORBIT parameter receives the segment number which contains the orbital and attitude information. The orbital and attitude information are required as input to the SMODEL and SORTHO programs. There is no attitude data for level 1B tape.

PCI wishes to acknowledge the assistance of Dr. Thierry Toutin for his assistance in this program. For more information about the method, please see the following papers:

 Toutin, Th, 1985.  Analyse mathematique des possibilites
 cartographiques du systeme SPOT, These de Docteur-Ingenieur
 en Sciences Geodesiques, ENSG, Paris, France, pp 1-163.

 Toutin, Th. & Carbonneau Y.  La Multi-Stereoscopie Pour Les
 Corrections D'Images SPOT-HRV, Canadian Journal of Remote
 Sensing, p110, Vol. 15, No. 2 September, 1989.
 (This article is also available in English from the Canada
 Centre for Remote Sensing.)

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EXAMPLE

The user has received a SPOT panchromatic left view SPOTIMAGE format tape and wishes to perform orthorectification on the data. To get a preliminary printout of the tape header and orbital information, the program MSH in the Tape I/O package can be run (this is optional).

 EASI>REPORT=
 EASI>STARTFIL=1
 EASI>RUN MSH

The user wishes to extract channel 1 from the tape and store them in the file irvinel.pix. Note: the created file would be approximately 36 Mbyte.

 EASI>FILE="irvinel.pix"
 EASI>MTIC=1
 EASI>TEX1="Irvine, Tape 1234"
 EASI>REPORT="irvinel.txt"
 EASI>R MSPOT

After the tape has completed reading, the text report file irvinel.txt could be printed using a print utility on your system, and the REPORT parameter should be reset to the terminal:

 EASI>REPORT="TERM"

The file irvinel.pix could now be used as input, along with collected ground control points, to the SMODEL and SORTHO programs.

NOTES ON ACCESSING TAPE DRIVES:

If you have trouble accessing the tape drive, you may have to set up the MT00 and MT0: parameters to allow tape reading programs (such as MSH and MSPOT) to access the drive. This is described in the Installation manual that was supplied with the PCI EASI/PACE software and should have been done by your system manager. In general you would do the following:

 EASI>MT00="MT0:"
 EASI>MT0:="device_name"    |e.g., "/dev/rmt0" on some UNIX systems

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