CDNLAPS -- CD NLAPS Format

Reads LANDSAT TM imagery from a NLAPS (NDF) format CD when satellite orthorectification is required. CDNLAPS automatically creates a PCIDSK file, reads all of the requested imagery channels from CD, and saves the satellite path information in a segment.

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

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

See Also: MEOSAT, SATORTHO, MSPOT, MLANDC, MSPOTC, CDSPOT, CDLANDC, CDEOSAT, SMODEL, SORTHO, SHL

PARAMETERS

CDNLAPS is controlled by the following global parameters: 

Name     Prompt                                  Count     Type
NLAPSHD  NLAPS Header File Name                  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
REPORT   Report Mode: TERM/OFF/filename          1-64      Char

The following parameter receives output:

ORBIT    Orbit Segment                           1         Int

NLAPSHD

Specifies the name of the NLAPS header file with full path. The header file has an extension ".hd". 

 EASI>NLAPSHD="/cdrom/lt501704.hd"

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

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"
Note: If TEX1 is defaulted, the following fields of the File Header in the output PCIDSK image database created will hold the following information: 

FH5   receives the tape ID, satellite Sensor and satellite Track.
FH7.1 receives the acquisition Date and scene Centre (longitude,
      latitude in decimal degrees.)
FH7.2 will be blanked for now.

REPORT

Specifies where the information report on the CD 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 CDNLAPS program is part of the satellite orthorectification package. It is used to read LANDSAT TM NLAPS format CD when satellite orthorectification is required. CDNLAPS automatically creates a PCIDSK file, reads all of the requested imagery channels from CD, and saves the satellite path information in a segment. Output from CDNLAPS is used with the SMODEL and SORTHO programs.

The EROS date centre makes available different levels of geodetic processing and product types. CD read by the CDNLAPS program must conform to the following specifications:

The CDNLAPS program will extract from the CD the geographic coordinates of the scene centre and the 4 corner points. If the corner points are in UTM coordinates, it will be extracted. If the corner points are in non-UTM coordinates, the LAT/LONG coordinates will be used to calculate the equivalent UTM coordinates. 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. The user should not expect very accurate results if the geographic coordinates are used. Also, if ephemeris data can be found from the TRAILER file, it will be used to calculate a more precise orbit.

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 CDNLAPS is run.

The ORBIT parameter receives the number of the segment which contains the orbital information. The orbital information in this segment is required as input to the SMODEL and SORTHO programs.

PCI wishes to acknowledge the assistance of Dr. Thierry Toutin for this software. 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 in Ottawa.)

EXAMPLE

The user has received a LANDSAT TM 6894 pixels x 6393 lines NLAPS format CD and wishes to perform orthorectification on the data. The user wishes to extract channels 1, 2, 3, 4, 5, and 7 from the CD, and store them in the file tm.pix. Note: the created file will be approximately 6 * 44 Mbytes = 264 Mbytes. 

 EASI>NLAPSHD="/cdrom/lt501704.hd"              | for UNIX machine
 EASI>NLAPSHD="D:\lt501704.hd"                  | for PC 
 EASI>NLAPSHD="[ABC.TM]lt501704.hd"             | for VMS machine
 EASI>NLAPSHD="CD_SAMPLE:lt501704.hd            | for MacOS
 EASI>FILE="tm.pix"
 EASI>CDIC=1,2,3,4,5,7
 EASI>TEX1="Florida, USA"
 EASI>REPORT="tm.txt"
 EASI>R CDNLAPS
After the CD has completed reading, the text report file tm.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 tm.pix could now be used as input, along with collected ground control points, to the SMODEL and SORTHO programs.

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