The GetTREValue method retrieves the value of selected TRE fields in a NITF or MIE4NITF file.
Example
e = ENVI(/HEADLESS)
File = FILEPATH('MultiSegmentExample.ntf', ROOT_DIR=e.ROOT_DIR, $
SUBDIRECTORY = ['data', 'NITFExamples'])
NITF = ENVINITF(File)
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
API Version
4.3
See Also
ENVINITF, ENVINITF::GetTREFields, ENVINITF::GetTRENames, NITF Tagged Record Extensions Background