The UpdateItem method updates the value of an existing format-specific or user-defined metadata item.

For ENVI-format rasters, the following standard metadata tags are reserved and cannot be used with the UpdateItem method: bands, byte order, coordinate system string, data type, file type, geo points, header offset, interleave, lines, map info, pixel size, projection info, rpc info, and samples.

To save metadata changes to disk, use the ENVIRaster::WriteMetadata method.


; Launch the application
e = ENVI()
; Create an ENVIRaster
file = FILEPATH('qb_boulder_msi', ROOT_DIR=e.ROOT_DIR, $
  SUBDIRECTORY = ['data'])
raster = e.OpenRaster(file)
view = e.GetView()
layer = view.CreateLayer(raster)
; Update Metadata band names
metadata = raster.METADATA
metadata.UpdateItem, 'BAND NAMES', ['BLUE','GREEN','RED','OTHER']
; Close the layer and re-create the new band names
; display in layer manager
layer = view.CreateLayer(raster)


ENVIRasterMetadata.UpdateItem, Tag, Value [, ERROR=variable]



The tag name of the metadata item you wish to update.


The value of the metadata item you wish to update.

Note: User-defined metadata is stored in the header (.hdr) file as a string. An array is stored as a vector of strings.


Keywords are applied only during the initial creation of the object.


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



API Version


See Also

ENVIRasterMetadata, ENVIRasterMetadata::AddItem, ENVIRasterMetadata::HasTag, ENVIRasterMetadata::RemoveItem, ENVIRaster's METADATA property, ENVIRaster::WriteMetadata