GCPPRO

Description

Converts the input segment or layer of Ground Control Points (GCPs) to GCPs in the specified output units and stores them in a second GCP segment or layer.

Parameters

Name	Type	Caption	Length	Value range
FILE *	String	Input file name	1 - 192
DBGC *	Integer	Input GCP segment to transform	1 - 2
FILM	String	Master file name	0 - 192
DBGEO	Integer	Input georeference segment	0 - 2	Default: 1
OUNITS	String	Output coordinate units	0 - 192
DBSN	String	Output GCP layer/segment name	0 - 192
DBSD	String	Output GCP layer/segment description	0 - 64
LASC	Integer	Last Segment Created	0 - 1

* Required parameter

Parameter descriptions

FILE

Specifies the name of the PCIDSK database file containing the GCP segment to project.

DBGC

Specifies the segment of Ground Control Points (GCPs) from FILE to transform.

If a second GCP segment is defined in FILE, this will be overwritten with the output GCPs. If no second GCP segment is specified, one will be created in FILE. Elevation values, if they exist, are copied as-is to the output GCP segment.

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.

FILM

Specifies the path and file name of the PCIDSK file to which the GCPs are tied. This parameter is required only if you are projecting a GCP segment that has GCPs in 'PIXEL' coordinates to FILM (master file) georeference units. If the GCP units are other than 'PIXEL', FILM is not required.

DBGEO

Specifies the georeference segment in FILM that defines the projection to which the GCPs are tied.

If the GCPs are in FILM 'PIXEL' coordinates, DBGEO(1) must have the projection bounds defined for FILM.
If the GCPs are not 'PIXEL', the GCP and projection units must be the same.
If DBGEO(2) is defined, this is the projection to convert to.

If unspecified, DBGEO uses segment 1 from FILM.

OUNITS

Specifies the units (projection system) of the output coordinates.

Valid units include:

LON or LAT: longitude / latitude
UTM zone_num: Universal Transverse Mercator; zone must be specified
UPS row: Universal Polar Stereographic; row must be specified
SPAF zone_num: State Place American Foot; eastings and northings zone must be specified
SPCS zone_num: State Plane Coordinate System; eastings and northings zone must be specified
SPIF zone_num: State Plane International Foot; eastings and northings zone must be specified
PIX: pixel / line coordinate

DBSN

Specifies a name (up to 8 characters) for the output GCP segment or layer.

If not defined, the name from the input GCP layer/segment is used.

DBSD

Describes (in up to 64 characters) the contents or origins of the output data.

If a description is not specified, the description from the input GCP layer/segment is used.

LASC

If a new GCP segment is created, the segment number for the new segment is saved in this output parameter.

Details

GCPPRO converts input Ground Control Points (GCPs) to the specified output units.

The specified input image database (FILE) contains the GCP segment to project (DBGC) and will receive the output GCP segment. The second file (FILM) contains the georeference segment to correct to. FILM must be defined only if you are projecting GCPs collected as FILM PIXELs to a different unit, or if DBGEO exists in a separate database. If the GCP segment is not in FILM PIXELs or if FILE is being used as FILM, FILM may be defaulted as FILE.

DBGEO(1) specifies the projection to which the GCPs are tied. If the GCPs are in FILM 'PIXEL' coordinates, the projection bounds for FILM must be defined in DBGEO(1) in order to convert from PIXEL to the DBGEO(1) units. If DBGEO(2) is defined, this defines the projection to which to convert the GCPs.

The GCP Layer Name (DBSN) and GCP Layer Description (DBSD) are used if specified, and a new GCP segment or layer is created. If unspecified, the name and/or description from the existing segment or layer are used.

The OUNITS (Output Coordinate Units) may be used for input and/or output respectively of the following special cases:

LON or LAT: longitude / latitude coordinates
UTM (and a zone): Universal Transverse Mercator eastings and northings
UPS (and a row): Universal Polar Stereographic eastings and northings
SPAF (and a zone): State Place American Foot eastings and northings
SPCS (and a zone): State Plane Coordinate System; eastings and northings
SPIF (and a zone): State Plane International Foot; eastings and northings
PIX: pixel / line coordinate

GCPPRO is a utility program that transforms Ground Control Points to the units required for certain programs. For example, most registration programs within EASI cannot convert between projections, so the GCP units must be converted to the output units to which you will be correcting.

GCPPRO is not required if the image correction is done using REGPRO. REGPRO performs the same conversion between projections that GCPPRO does.

GCPPRO will not process conversion between more than two projections. GCPPRO can convert between "PIXEL" and a georeference segment, if the bounds have been defined in DBGEO. As such, GCPPRO can perform any of the following transforms:

The GCP units and OUNITS are both special cases. For example:
```
GCP units OUNITS "UTM 11 S E000" ---> "LONG/LAT E000"
```
The projection for the GCPs are defined in DBGEO(1). The DBGEO(1) and GCP units must be the same.

For example:
```
DBGEO(1) and GCP units OUNITS "UTM 11 S E000" ---> "LONG/LAT E000"
```
The projection for the GCPs are defined in DBGEO(1) and the output GCP projection is defined in DBGEO(2). The DBGEO(1) and GCP units must be the same.

For example:
```
DBGEO(1) and DBGEO(2) GCP units units "UTM 11 S E000" ---> "LONG/LAT E000"
```
The GCPs were collected as FILM PIXELs corresponding to DBGEO(1). DBGEO(1) must have the bounds defined in the projection units and the image is assumed to have already been corrected to overlay the DBGEO(1) projection.

For example:
```
GCP DBGEO(1) DBGEO(2) units units units "PIXEL" ---> "UTM 11 S E000" ---> "LONG/LAT E000"
```
The GCPs were collected in FILM DBGEO(1) units. Output them as PIXEL units derived from DBGEO(2) and specified with OUNITS. DBGEO(2) must have the bounds defined in the projection units.

For example:
```
DBGEO(1) DBGEO(2) units units OUNITS "UTM 11 S E000" ---> "LONG/LAT E000" ---> "PIXEL"
```

Example

Image "irvine.pix" has a GCP segment (segment 27) that was collected in "eltoro.pix" "PIXEL" coordinates. As "eltoro.pix" has been already been geometrically corrected to overlay the "UTM 11 S E000" projection, the GCPs can be transformed with GCPPRO. (The following example should not be used if the GCPs are "PIXEL", but the image they are tied has not been geometrically corrected already to overlay with the DBGEO(1) projection units.). In the following example, the GCPs will be transformed as follows:

"PIXEL" ---> "UTM 11 S E000" ---> "LONG/LAT E000" Segment 1 OUNITS on "eltoro.pix" of "LON E0"

As the output units are the special case of "LON", this could be defined either with an output georeference segment (DBGEO(2)) or with OUNITS. If the output units were not a special case listed for OUNITS, DBGEO(2) would have to be defined.

EASI>FILE="irvine.pix"
EASI>DBGC=27           ! Create a new segment for output
EASI>FILM="eltoro.pix"
EASI>DBGEO=            ! DBGEO(1) will be 1
EASI>OUNITS="lon e0"   ! Output    as "LONG/LAT    E000"
EASI>DBSN=             ! Use DBSN from DBGC
EASI>DBSD=             ! Use DBSD from DBGC
EASI>MONITOR=          ! Default to ON

EASI>R GCPPRO

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