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	Length	Value range
Raster File Name *	String	1 -
Output: Output file name *	Raster port	1 -
OutputRPC: Rational Function layer *	BIN port	1 -
CD Input Layer(s) List	Integer	0 - 4	1 -
File Description	String	0 - 1
Report	String	0 - 192	See parameter description

* Required parameter

Parameter descriptions

Raster File Name

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.

Output: Output file name

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

OutputRPC: Rational Function layer

Specifies the output Rational Function layer that describes the math model of the image.

CD Input Layer(s) List

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

File Description

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.

Report

Specifies where to direct the generated report.

Available options are:

• LOG: generates a report on the terminal (default)
• <modulename.RPT>: appends a report to the module's RPT file
• DISK: generates a report on file "IMPRPT.LST"

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.

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.

References

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