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ENVINITFMetadata

ENVINITFMetadata

This function returns an IDL dictionary of NITF metadata from a specified NITF raster. The top-level dictionary is a collection of IDL lists and dictionaries that contain the various segments of metadata: header, image, text, annotation (graphics), and data extension segments (DESes).

The collection of NITF metadata is a superset of the NITF metadata that is displayed in the NITF Metadata Viewer (accessed from the Data Manager or Layer Manager).

See NITF API Metadata Background for details.

Example


This example prints the number of bands in each image segment of a NITF raster. Copy and paste the example into a new window in the IDL Editor. Save the file as NitfMetadataExample.pro, then compile and run the program.

PRO NitfMetadataExample
COMPILE_OPT IDL2
 
  ; Start the application
  e = ENVI(/HEADLESS)
   
  ; Select a NITF raster
  file = FILEPATH('MultiSegmentExample.ntf', $
    ROOT_DIR=e.ROOT_DIR, SUBDIR=['data','NITFExamples'])
  raster = e.OpenRaster(file)
   
  ; Get the metadata
  metadata = ENVINITFMetadata(raster)
  numImages = N_ELEMENTS(metadata.Image)
   
  FOR i=0, numImages-1 DO BEGIN
    Print, metadata.Image[i].NBANDS
  ENDFOR
END

IDL prints:

    1
    1
    1
    1
    1

This file has five image segments, each with one band.

Syntax


Result = ENVINITFMetadata(InputRaster, KEYWORDS=value)

Return Value


This function returns an IDL dictionary of NITF metadata:

  • With one input raster, it returns metadata for a single image segment.
  • With an array of input rasters, it returns metadata for multiple image segments.
  • With one or more input rasters and the ALL keyword set, it returns metadata for all segments.
  • With one or more input rasters and the HEADER keyword set, it returns metadata for the header segment only.

Arguments


InputRaster

Specify an ENVIRaster in NITF format. You can only open one NITF file at a time using the ENVI::OpenRaster method. If the NITF file has multiple image segments, then the ENVI::OpenRaster method returns an array of ENVIRasters, which you can pass into ENVIRasterMetadata. You can also specify a subset of this array, as the following example shows:

  file = FILEPATH('MultiSegmentExample.ntf', $
    ROOT_DIR=e.ROOT_DIR, SUBDIR=['data','NITFExamples'])
  raster = e.OpenRaster(file)
  metadata = ENVINITFMetadata([raster[0], raster[2], raster[4]])

If the NITF file only has one image segment, then ENVI::OpenRaster returns a single ENVIRaster, which you can pass into ENVIRasterMetadata.

Keywords


ALL

Set this keyword to return the metadata from all available NITF segments: header, image, annotation, text, and DES.

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.

HEADER

Set this keyword to only return header segment metadata.

NO_DATA

Set this keyword to return metadata without any DATA_* values. This reduces the size of the returned metadata collection. The DATA_* values are optional, so use the HasKey method to determine if any DATA_* keys are present, for example:

IF (metadata.HasKey('DATA_LUT') THEN BEGIN
  Print, metadata.Image[0].Band[1].DATA_LUT
ENDIF

Version History


ENVI 5.3, Service Pack 1

Introduced

API Version


3.2

See Also


NITF/NSIF Background, NITF Tagged Record Extensions Background, Save NITF Files

 



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