The Get method retrieves all of the ground control points (GCPs) in an ENVIGCPSet object.

While a PRINT command on an ENVIGCPSet object will list all of the GCPs, the Get method lets you access the actual GCP data.


; Start the application
e = ENVI()
; Open an existing GCP file
GCPFile = Dialog_Pickfile(TITLE='Select an ENVI .pts file')
; Return a list of all GCPs as an array of structures
All = GCPs.Get()
Print, All
; Return a list of one GCP (whose ID is 0) as a structure
Number0 = GCPs.Get(0)
Print, Number0


Result = ENVIGCPSet.Get([CoordSys] [, ID] [, ERROR=variable])

Return Value

This method returns one of the following:

  • An array of structures, if you do not specify the ID argument.
  • A structure, if you specify a valid ID argument.



Set this optional argument to an ENVICoordSys object, if you want to return the GCPs in a specific projection.


Set this optional argument to a valid identifier of an individual GCP that you want to retrieve. Use the PRINT command on the ENVIGCPSet object to obtain ID numbers, if needed.



Set this keyword to a named variable that will contain any error message issued during execution of this routine. If no error occurs, the ERROR variable will be set to a null string (''). If an error occurs and the routine is a function, then the function result will be undefined.

When this keyword is not set and an error occurs, ENVI returns to the caller and execution halts. In this case, the error message is contained within !ERROR_STATE and can be caught using IDL's CATCH routine. See IDL Help for more information on !ERROR_STATE and CATCH.

See Manage Errors for more information on error handling in ENVI programming.

Version History

ENVI 5.1


API Version


See Also