CDSPOTRPC

Description

CDSPOTRPC reads SPOT DIMAP and CAP imagery from a TIFF-format CD when satellite orthorectification using the Rational Function model is required. CDSPOTRPC automatically creates a PCIDSK file, reads all the requested imagery channels from CD, and saves the satellite path information to a segment. The output file from CDSPOTRPC is used as input to CATALYST Professional OrthoEngine.

Parameters

Name	Type	Caption	Length	Value range
FILI *	String	Input file name	1 - 192
FILO *	String	Output file name	1 - 192
LINKFILE	String	Create linked file: NO/YES	0 - 3
CDIC	Integer	CD input channel(s)	0 - 4	1 -
TEX1	String	Descriptive text	0 - 64
MMSEG	Integer	Output math model segment	0 - 1
REPORT	String	Report mode	0 - 192	Quick links

* Required parameter

Parameter descriptions

FILI

Specifies the full path and file name of the input product image file. For DIMAP format products, this is the IMAGERY.TIF file. For CAP format products, this is the IMAG_nn.DAT file, where nn represents the product number; this is typically set to 01.

FILO

Specifies the name of the PCIDSK file that will receive the processed data. The output file is created automatically and must not already exist.

LINKFILE

Instead of creating a new PCIDSK FILO to read the data from FILI, this parameter will create an output file in which the image channel is linked to the original imagery channel. The orbital segment will still be created in FILO. The default value is NO.

CDIC

Specifies the list of channels or layers to read from the CD. Up to 4 channels may be specified.

For each channel, a corresponding channel is created in the output PCIDSK file. Duplicate channels are NOT allowed.

If LINKFILE is set to YES, all channels will be linked.

If this parameter is not specified, all channels will be transferred.

Ranges of channels or segments can be specified with negative values. For example, {1,-4,10} is internally expanded to {1,2,3,4,10}. When you are not specifying a range in this way, only 48 numbers can be specified explicitly.

TEX1

Optionally specifies a line of text that describes the file. Typically, this contains information that identifies the location of the data and the CD reference number.

MMSEG

MMSEG is an output parameter. Upon completion, CDSPOTRPC writes the number of the output math model segment containing the computed math model to this parameter. This value may be used as input for other functions.

REPORT

Specifies where to direct the generated report.

Available options are:

• TERM: generates a report on the terminal (default)
• DISK: generates a report on file "IMPRPT.LST"
• OFF: turns off report generation
• <filename>: appends a report to the specified file

Details

CDSPOTRPC is part of the satellite orthorectification component. It reads SPOT DIMAP or CAP format products when satellite orthorectification is required. The corresponding metadata file (METADATA.DIM for DIMAP, LEAD_nn.DAT for CAP) must exist in the same directory as the image file. CDSPOTRPC automatically creates a PCIDSK file, reads the imagery channels from the product directory, and generates a Rational Function Model segment for the file. The output is used in CATALYST Professional OrthoEngine.

CDSPOTRPC uses the geometric metadata given with the image product to generate a dense point grid using a physical model of the sensor. A set of Rational Polynomial Coefficients is then computed for the scene and stored in a Rational Function Segment. OrthoEngine can then be used to measure GCPs and estimate image space corrections to the RPCs. In most cases, a simple 0th order correction is sufficient; it is sometimes necessary, however, to use a first-order correction polynomial.

If LINKFILE is set to NO, the generated file is automatically created with the dimensions required to hold all of the requested data. Ensure that sufficient disk space is available before running CDSPOTRPC. If LINKFILE is set to YES, the image channel is not created; it is linked to the image channel of FILI.

The output .pix file is approximately georeferenced in the nearest WGS84 UTM zone by projecting the four corner coordinates to an ellipsoidal height of zero meters. This georeferencing is merely nominal and should not be used for photogrammetric work; it is meant only to permit a user to view the scene in its approximate location with respect to surrounding features.

Example

The user has received a DIMAP format SPOT5 Level 1A product on CD and wishes to perform orthorectification on the data. The user wishes to generate RPCs and store them in the file spot5.pix.

EASI>FILI="SCENE01/IMAGERY.TIF"
EASI>FILO="spot5.pix"
EASI>LINKFILE="NO"
EASI>CDIC=1,2,3,4
EASI>TEX1="Richmond Hill, Canada"

EASI>R CDSPOTRPC

References

SPOT Image (2002). "SPOT Satellite Geometry Handbook", Edition 1, revision 0. SPOT document S-NT-73-12-SI.