CDSPOT -- CD SPOTIMAGE SPOT Format

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

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

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

See Also: SATORTHO, MLANDC, MSPOT, MSPOTC, MEOSAT, CDLANDC, MODEL, SORTHO, SDEM, SEPIPRO, SDEMCPY, SDEMMAN, SHL

PARAMETERS

CDSPOT is controlled by the following global parameters:

Name     Prompt                                  Count     Type
CDDIR    CD Directory                            1-64      Char
FILE     Database File Name                      1-64      Char
CDIC     CD Input Channel list                   1-16      Int
TEX1     Database Descriptive Text 1             0-64      Char
SPFILE   Scene Parameter File                    0-64      Char
REPORT   Report Mode: TERM/OFF/filename          1-64      Char

The following parameter receives output:

ORBIT    Orbit Segment                           1         Int

CDDIR

Specifies the name of the CD directory. All files should be contained inside the directory.

 EASI>CDDIR="cddir"

See example on how to enter CDDIR for different operating systems.

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"

CDIC

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

 EASI>CDIC=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 CD and there are 3 channels on a SPOT multispectral CD. 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 CDSPOT 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 CD reference number.

 EASI>TEX1="string"

SPFILE

Specifies the filename for the scene parameter text file output. For PCI Satellite and Orthorectification package, this parameter does not need to be specified. If SPFILE exists with the filename, the existing file is deleted before the new file is created.

 EASI>SPFILE="filename"       | Defining the output filename
 EASI>SPFILE=                 | Default, no scene parameter file
                              | is output

NOTE: SPFILE is only output for SPOT IMAGE CCT 1A CD. If the data is processed at a level higher than 1A, a warning (E108, "Option not available") is displayed and the imagery is read from CD but no SPFILE is created.

REPORT

Specifies where the CD information report should be directed. This report contains CD 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"    | switch off report generation

ORBIT

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

DETAILS

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

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

The CDSPOT program will extract from the CD 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 CD. 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 CDSPOT 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 CD and 1 channel on a SPOT panchromatic CD.

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 CD.

For PCI satellite and orthorectification package, SPFILE does not need to be specified.

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.)

EXAMPLE

The user has received a SPOT panchromatic left view SPOTIMAGE format CD and wishes to perform orthorectification on the data. The user wishes to extract channel 1 from the CD scene02 directory and store them in the file irvinel.pix.

 EASI>CDDIR="/cdrom/scene02/"   | for UNIX machine
 EASI>CDDIR="D:\SCENE02\"       | for PC
 EASI>CDDIR="[ABC.SCENE02]"     | for VMX machine

 EASI>FILE="irvinel.pix"
 EASI>CDIC=1
 EASI>TEX1="Irvine  CD 1234"
 EASI>SPFILE=
 EASI>REPORT="irvinel.txt"
 EASI>R CDSPOT

After the CD 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 irvine.pix could now be used as input, along with collected ground control points, to the SMODEL and SORTHO programs.

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