View Metadata

Use View Metadata to view detailed properties of the following types of data:

Double-click the layer name in the Layer Manager, or right-click and select View Metadata. The Metadata Viewer appears. Here are some tips for working with the Metadata Viewer:

Most metadata fields are self-explanatory, however some groups of metadata require further explanation:

Calibration Metadata

See the Radiometric Calibration topic for a list of sensors that ENVI automatically reads spectral calibration metadata from. The Metadata Viewer will then show the following fields (per band) under the "Spectral" category:

The following fields are listed under the "Image Parameters" category:

The following fields are listed under the "Supplementary" category:

If you save a dataset from any of these sensors to ENVI raster format, the accompanying header file (.hdr) will contain the following metadata fields: band names, bbl, cloud cover, data gain values, data offset values, fwhm, solar irradiance, sun azimuth, sun elevation, and wavelength.

Note: If you are programming with the ENVI API, all inherent metadata (including calibration parameters) is stored in memory as a property to the raster object. See ENVIRaster and ENVIRasterMetadata for more information.

References:

Chander, G., B. Markham, and D. Helder, "Summary of current radiometric calibration coefficients for Landsat MSS, TM, ETM+, and EO-1 ALI sensors," Remote Sensing of Environment 113 (2009): 893-903.

Irons, J., J. Dwyer, and J. Barsi, "The next Landsat satellite: The Landsat Data Continuity Mission," Remote Sensing of Environment 122 (2012): 11-21.

The Astronomical Almanac for the Year 2013. Joint publication of the U.S. Naval Observatory and Her Majesty's Nautical Almanac Office. St. Louis, MO: US Government Printing Office, 2012.

Acquisition Time

ENVI reads data acquisition time for ENVI-format files if the accompanying header file (.hdr) contains an acquisition time value. The acquisition time is listed under the "Time" category of the Metadata Viewer.

For Landsat, Pleiades, SPOT, QuickBird, and WorldView files, ENVI reads the data acquisition time from the metadata files distributed with the imagery.

If you save an image from any of these sensors to ENVI format, an acquisition time field will be added to the ENVI header file.

Note: If you are programming with the ENVI API, all inherent metadata (including acquisition time) is stored in memory as a property to the raster object. See ENVIRaster and ENVIRasterMetadata for more information. You can also create an ENVITime object that stores the acquisition time for a given raster dataset.

NITF Metadata

Use the NITF Dataset Browser to view metadata for NITF datasets including header information, tagged record extensions (TREs), data extension segments (DESes), annotation segments, and text segments. The metadata displayed in each item vary per different versions of NITF.

You can also write a script to view NITF metadata using the ENVINITFMetadata function.

See NITF Metadata Icons for a description of each item. Metadata are grouped as follows:

File Header

Image Segment

Text Segment (if present)

Data Extension Segments (DESes, if present)

Annotation Segments (if present)

Note: Header and segment fields are described in MIL-STD-2500C and MIL-STD-2500A.

NITF Metadata Icons

The following icons appear in the NITF Dataset Browser to identify the types of metadata that may appear in a particular container:

Container

Icon

Description

File Header

Contains metadata common to the entire NITF file. It may also include tags (TREs) or security metadata pertaining to the entire file.

Security

Contains security metadata for the file, image segment, text segment, or data extension segment (DES).

TRE





A white icon contains metadata for a TRE that cannot be edited.

A green icon contains editable metadata for the TRE.

A blue icon contains TREs from a TRE Overflow DES.

DES

Contains Data Extension Segments (DESes). It may also include security metadata and user-defined subheader fields.

Single-band Image Segment

Contains image metadata for a single-band image segment. It may also include security metadata, image comments, and TRE metadata containers.

Multi-band Image Segment

Contains image metadata for a multiple-band image segment. It may also include security metadata, image comments, and TRE metadata containers.

Text Segment

Contains metadata for a text segment.

TIFF Metadata

For TIFF and GeoTIFF image files, you can optionally use the Edit ENVI Header tool or a text editor to create an ENVI header file (.hdr) to override the default metadata fields. For example, you can change the default stretch type to better visualize the data or you can change the wavelength information if you know that it is wrong in the original TIFF/GeoTIFF file. Once you save the changes to a header file, ENVI will read the new metadata values when you re-open the image file.

Raster Series Metadata

These metadata fields pertain to spatiotemporal series files (.series) that were created with ENVI's Build Raster Series tool.

See Also

ENVI Header Files, Optional ENVI Header Fields, Edit Raster Metadata, Edit NITF Metadata, Supported Data Types, ENVIRasterMetadata (API), ENVIRaster::WriteMetadata (API)