ENVINITF::GetTREValue

The GetTREValue method retrieves the value of selected TRE fields in a NITF or MIE4NITF file.

Example

; Start the application

e = ENVI(/HEADLESS)

; Open a NITF file

File = FILEPATH('MultiSegmentExample.ntf', ROOT_DIR=e.ROOT_DIR, $

  SUBDIRECTORY = ['data', 'NITFExamples'])

NITF = ENVINITF(File)

; Get the value of the ASSOCTRY field in a PIAPEA TRE

TREValue = NITF.GetTREValue('Text', 0, 'PIAPEA', 'ASSOCTRY')

Print, TREValue

Result:

US

Syntax

Result = ENVINITF.GetTREValue(Type, Index, TREName, TREField [, Keywords=value])

Return Value

This method returns a string or string array with the values of a TRE field.

Arguments

Type

Specify a string with the segment type from which to retrieve TRE names. Strings are not case-sensitive. The choices are:

Header

Image

Text

Or, specify the name of a MIE4NITF camera series; for example: series0, series1, etc.

Index

Specify an integer with the index number of a segment or a frame in a series.

TREName

Specify a TRE name from which to retrieve fields. Use the GetTRENames method to get TRE names.

TREField

Specify a TRE field name to query. Use the GetTREFields method to get TRE names.

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.

TRE_INDEX (optional)

Set this keyword to a zero-based index number of a specific TRE when multiple TREs exist with the same name. If you do not set this keyword and more than one TRE matches the given TRE name, the first TRE found will be used. If only one TRE matches the given name, then this keyword is ignored.

Version History

ENVI 5.6.1

Introduced

API Version

4.2