GCPWRIT

Description

Parameters

Parameter descriptions

InputGCP: Input GCP segment or layer

The input GCP layer or segment to read.

Output GCP text file

The path and file name of the output text file to which to write the GCP coordinates.

For more information on the required format for the text file, see the description of the GCP format (GCPFORM) parameter.

GCP format

The code for the format of the input GCP data.

The codes are described as follows:

• 2D: ID P L X Y S
• 2DERR: D P L X Y eP eL eX eY S
• 3D: ID P L X Y Z S
• 3DERR: ID P L X Y Z eP eL eX eY eZ S
• BULK: ID S X Y Z PhotoID P L PhotoID P L ...

where:

• ID: true GCP or check point GCP ID
• P, L: pixel and line values
• X, Y, Z: georeferenced x, y, and z values
• eP, eL: pixel and line error values
• eX, eY, eZ: x, y, and z error values
• S: "G" for active GCPs, "I" for inactive GCPs, and "C" for check-point GCPs
• PhotoID: Image ID that corresponds to the pixel and line coordinates of each GCP

Deg/Min/Sec format

This check box is clear by default, which means the output coordinates of longitude and latitude use real numbers or degrees/minutes/seconds/hemisphere strings. When selected, the latitude and longitude values are written to the output text file in DMS format. Apostrophe (') and quotation (") symbols are used as separators between degrees, minutes, seconds, and hemisphere strings.

This parameter is ignored if vector units are not LONG/LAT.

The DMS format for latitude and longitude is as follows:

• latitude: [integer degrees]d[integer minutes]'[floating point seconds]"[N|S]
• longitude: [integer degrees]d[integer minutes]'[floating point seconds]"[E|W]

where N, S, E, and W stand for the north, south, east, and west hemispheres, respectively.

For example:

latitude: 34d01'15.1104"N
longitude: 118d14'14.2080"W

Details

The GCPWRIT algorithm writes GCP data from a specified GCP segment or layer to a text file. The GCP data may include check-point data. To specify the format of the GCP data in the output text file, you use the GCP format (GCPFORM) and Deg/Min/Sec format (DMSFORM) parameters.

A GCP may be intended for use with georeferencing control (a "true GCP"), or it may be intended for use in assessing the accuracy of a rectification result (a "check point" or a "check-point GCP"). The data written to the output text file includes a flag value (S) that distinguishes between the two.