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ENVIGCPSet::ApplyOffset

ENVIGCPSet::ApplyOffset

The ApplyOffset function method subtracts a designated pixel offset from all of the GCPs in an ENVIGCPSet object. Use this method when applying GCPs from a full input image to a spatially subsetted image with the ENVIRPCOrthorectificationTask task.

If you set the OUTPUT_SUBSET property on ENVIRPCOrthorectificationTask, you do not need to use the ApplyOffset method.

Example


The following example shows the use of ApplyOffset with a spatially subsetted image.

; Start the application
e = ENVI()
 
; Open an image file
ImageFile = Dialog_Pickfile(TITLE='Select an input image')
Raster = e.OpenRaster(ImageFile)
 
; Create a spatial subset of the image file
RasterSubset = ENVISubsetRaster(Raster, SUB_RECT=[200, 300, 400, 400])
 
; Open a DEM
DEMFile = Dialog_Pickfile(TITLE='Select a DEM file')
DEM = e.OpenRaster(DEMFile)
 
; Open a ground control point (GCP) file
GCPFile = Dialog_Pickfile($,
   TITLE='Select a GCP shapefile or ENVI .pts file')
GCPs = ENVIGCPSet(GCPFile)
 
; Adjust the GCPs for the spatial subset
NewGCPs = GCPs.ApplyOffset(200, 300)
 
; Get the RPC orthorectification task
Task = ENVITask('RPCOrthorectification')
 
; Define parameters for the task
Task.Input_Raster = RasterSubset
Task.DEM_Raster = DEM
Task.Input_GCP = NewGCPs
Task.Output_Raster_URI = e.GetTemporaryFilename()
 
; Run the task
Task.Execute, ERROR=error
RasterSubset.Close

Syntax


Result = ENVIGCPSet.ApplyOffset(xOff, yOff [, ERROR=variable])

Return Value


This method returns a reference to a new ENVIGCPSet object.

Arguments


xOff

The subset x1 value

yOff

The subset y1 value

Keywords


ERROR

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

Introduced

API Version


3.2

See Also


ENVIGCPSet



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