GCPREFN

Description

GCPREFN refines the ground control points (GCP) of a GCP segment in a raw image file by using a computed sensor model or a polynomial equation, and then exports the refined GCPs to a new GCP segment.

Parameters

Name	Type	Length	Value range
InputGCP: GCP Layer to be Refined *	GCP port	1 - 1
InputORB: Orbit Layer	ORB port	0 - 1
InputMM: Math Model Layer	BIN port	0 - 1
Output: GCP Layer with GCPs Refined *	GCP port	1 - 1
Model Type *	String	2 - 1	SAT \| RF \| AP \| POLY \| ADS \|RS
Polynomial Order	Integer	0 - 1	-2 - 8 Default: 0
Rejection Method	Float	0 - 3
Number of GCPs to Reject	Integer	0 - 1
Percentage of GCPs to Reject	Float	0 -
Rejection Ratio (X to Y)	Float	0 - 1
Minimum X Standard Deviation	Float	0 - 1
Minimum Y Standard Deviation	Float	0 - 1
Minimum X Absolute Residual	Float	0 - 1
Minimum Y Absolute Residual	Float	0 - 1
Minimum X RMS Error	Float	0 - 1
Minimum Y RMS Error	Float	0 - 1
Thinning Option	String	0 - 1	Default: Inactive
Number of GCPs accepted	Integer	0 - 1024
Number of GCPs rejected	Integer	0 - 1024
Number of checked GCPs	Integer	0 - 1024
Original residual error (X) of accepted GCPs	Integer	0 - 1024
Original residual error (Y) of accepted GCPs	Integer	0 - 1024
New residual error (X) of accepted GCPs	Integer	0 - 1024
New residual error (Y) of accepted GCPs	Integer	0 - 1024
Residual error (X) of rejected GCPs	Integer	0 - 1024
Residual error (Y) of rejected GCPs	Integer	0 - 1024
Residual error (X) of checked GCPs	Integer	0 - 1024
Residual error (Y) of checked GCPs	Integer	0 - 1024
Report	String	0 - 192	See parameter description

* Required parameter

Parameter descriptions

InputGCP: GCP Layer to be Refined

The GCP segment or layer number that contains the set of GCPs to refine. The segment or layer must be in a georeferencing unit other than pixels.

InputORB: Orbit Layer

If the satellite ortho model, specified by the Model Type (MODELTYP) parameter, is used to remove inaccurate GCPs from a raw satellite scene, this parameter specifies the orbit layer that contains the ephemeris data for the input raw image. If you specify POLY (Polynomial) as the model type, you need not specify a value for this parameter.

InputMM: Math Model Layer

The math-model layer that contains the math model to use for the refinement.

Output: GCP Layer with GCPs Refined

The output GCP layer containing the refined GCPs.

Model Type

The model type to use in refining the GCPs.

The following options are available:

SAT: Toutin's Model
RF: Rational Function Model
AP: Airphoto Model
POLY: Polynomial
ADS: (Leica Airborne Digital Scanner)
RS: Radar Model

Polynomial Order

The polynomial transformation order number for the Polynomial or Rational Function Model.

Rejection Method

The method to use to reject GCPs.

If no value is specified for this parameter, GCPREFN uses the root-mean-square (RMS) error-rejection method by default, with the values for the minimum x and y RMS set to 2.0.

In the Rejection Method list, select one of the following:

Absolute Number (1) is the absolute number of GCPs to reject, starting with the ones with the highest residual. When you select this option, you must specify a value for Number of GCPs to Reject and Rejection Ratio (X to Y).
Percentage Number (2) is the percentage of the points that can be rejected, starting with the one with the highest residual. When you select this option, you must specify a value for Percentage of GCPs to Reject and Rejection Ratio (X to Y).
Standard Deviation (3) is the sigma (standard deviation) rejection method. When you select this option, you must specify a value for Minimum X Standard Deviation and Minimum Y Standard Deviation.
Absolute Distance (4) is the absolute distance rejection of the residuals. When you select this option, you must specify a value for Minimum X Absolute Residual and Minimum Y Absolute Residual.
RMS Error (5) is the RMS-error-rejection method. When you select this option, you must specify a value for Minimum X RMS Error and Minimum Y RMS Error.

Number of GCPs to Reject

Available when Absolute Number (1) is selected for Rejection Method, the absolute number of GCPs to reject, starting with the ones with the highest residual. For example, to reject 10 GCPs, enter 10.

Note: When you specify a value for this parameter, you must also enter a value for Rejection Ratio (X to Y).

Percentage of GCPs to Reject

Available when Percentage Number (2) is selected for Rejection Method, the percentage of the number of GCPs to reject. For example, to reject 5 percent of the GCPs, enter 5.

Note: When you specify a value for this parameter, you must also enter a value for Rejection Ratio (X to Y).

Rejection Ratio (X to Y)

Available when Absolute Number (1) or Percentage Number (2) is selected for Rejection Method, the ratio weighting between the x and y residuals. For example, to give twice the weight to the x-residual as the y-residual, enter 2. When a point has an x-residual of 0.4 and a y-residual of 0.5, the point will be given an x-residual of 0.8 and a y-residual of 0.5 for the rejection.

Note: When you specify a value for this parameter, you must also enter a value for either Number of GCPs to Reject or Percentage of GCPs to Reject based on your selection for Rejection Method.

Minimum X Standard Deviation

Available when Standard Deviation (3) is selected for Rejection Method, the minimum standard deviation value of the x-residual to reject. For example, to reject points with a standard deviation higher than two of the x-residual, enter 2.

Note: When you specify a value for this parameter, you must also enter a value for Minimum Y Standard Deviation.

Minimum Y Standard Deviation

Available when Standard Deviation (3) is selected for Rejection Method, the minimum standard deviation value of the y-residual to reject. For example, to reject points that have a standard deviation of higher than one of the y-resolution mean, enter 1.

Note: When you specify a value for this parameter, you must also enter a value for Minimum X Standard Deviation.

Minimum X Absolute Residual

Available when Absolute Distance (4) is selected for Rejection Method, the minimum absolute x-residual to reject. The rejection starts from the point with the greatest x-residual distance. For example, to reject points with an x-residual greater than three-quarters of a pixel, enter 0.75.

Note: When you specify a value for this parameter, you must also enter a value for Minimum Y Absolute Residual.

Minimum Y Absolute Residual

Available when Absolute Distance (4) is selected for Rejection Method, the minimum absolute y-residual to reject. The rejection starts from the point with the greatest y-residual distance. For example, to reject pixels with a y-resolution greater than three-quarters of a pixel, enter 0.75.

Note: When you specify a value for this parameter, you must also enter a value for Minimum X Absolute Residual.

Minimum X RMS Error

Available when RMS Error (5) is selected for Rejection Method, the minimum x-RMS error. For example, to reject points with an x-RMS greater than three-quarters of a pixel, enter 0.75.

Note: When you specify a value for this parameter, you must also enter a value for Minimum Y RMS Error.

Minimum Y RMS Error

Available when RMS Error (5) is selected for Rejection Method, the minimum y-RMS error. For example, to reject points with a y-RMS greater than three-quarters of a pixel, enter 0.75.

Note: When you specify a value for this parameter, you must also enter a value for Minimum X RMS Error.

Thinning Option

Whether to write rejected points. When you specify Inactive, GCPs that have been converted to inactive points are written to the newly created GCP segment. When you specify Delete, the converted GCPs are omitted. In all other cases, an error is generated.

Tip: When you specify Inactive, you can see which written points remain as GCPs and which became inactive by viewing the segment in CATALYST Professional Focus. On the Files tab in Focus, right-click the GCP segment, and then click View.

Number of GCPs accepted

On completion of processing, the total number of GCPs accepted.

Number of GCPs rejected

On completion of processing, the total number of GCPs rejected.

Number of checked GCPs

On completion of processing, the total number of GCPs verified.

Original residual error (X) of accepted GCPs

On completion of processing, the original x-residual error of all accepted GCPs.

Original residual error (Y) of accepted GCPs

On completion of processing, the original y-residual error of all accepted GCPs.

New residual error (X) of accepted GCPs

On completion of processing, the new x-residual error of all accepted GCPs.

New residual error (Y) of accepted GCPs

On completion of processing, the new y-residual error of all accepted GCPs.

Residual error (X) of rejected GCPs

On completion of processing, the x-residual error of all rejected GCPs.

Residual error (Y) of rejected GCPs

On completion of processing, the y-residual error of all rejected GCPs.

Residual error (X) of checked GCPs

On completion of processing, the x-residual error of all verified GCPs.

Residual error (Y) of checked GCPs

On completion of processing, the y-residual error of all verified GCPs.

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

GCPREFN removes GCPs with large errors from GCP segments. The algorithm reads the GCPs from the GCP segment specified for InputGCP (DBGC) in the database file. The GCP segment must be in a georeferencing unit other than pixels.

With the Model Type (MODELTYP) parameter, you select a polynomial equation or a satellite ortho model to use to remove inaccurate GCPs. When Model Type (MODELTYP) is Toutin's Model (SAT), you must also specify an orbital segment. GCPREFN extracts the ellipsoid from the GCP segment.

For more information about the rejection methods you can use, see Rejection Method .

GCPREFN saves the final GCPs and writes them to a new GCP segment.

Note: GCPREFN does not use refined GCPs to create or update an output math-model segment. To compute a model with updated GCPs, use a specific modeling algorithm, such as RFMODEL, RSMODEL, SATMODEL, APMODEL, or OEMODEL. For more information about any of the preceding algorithms, follow the link to each under Related functions.

Note: If you specify a segment that includes inactive GCPs or check points, they will be copied to the output segment. That is, they are not included in the refinement process.

On completion, GCPREFN updates the various output parameters with statistics about GCPs.

Environments	PYTHON :: EASI :: MODELER
Batch Mode	Yes
Quick links	Description :: Parameters :: Parameter descriptions :: Details :: Related

GCPREFN

GCP refinement

Description

Parameters

Parameter descriptions

Details