Use the View Metadata dialog to view details of these data:

  • Rasters
  • NITF files
  • Vectors
  • Raster Color Slices
  • Classifications
  • Annotations

To view the metadata:

  • In the Layer Manager, right-click the layer and select View Metadata.
  • in the Data Manager, right click the file and select View Metadata.

The View Metadata dialog appears. For descriptions of the typical metadata fields, see ENVI Header Fields.

Here are some tips for the View Metadata dialog:

  • Select a category on the left side of the dialog to see values for each of its properties. An example category is Raster, and an example property for Raster is Dataset.
  • The Coordinate System category displays map properties for datasets georeferenced to a geographic or projected coordinate system. An RPC Map Info category is available for datasets mapped with rational polynomial coefficients (RPCs) instead of a map projection. This category displays the properties of the coefficients.
  • If you opened a georeferenced dataset into the view, you can see the coordinate system properties of the view. Right-click on a view name in the Layer Manager and select View Properties.
  • To export the properties for the selected category (or all categories) to a text file, select a category on the left side of the dialog and select what you want to export from the Export drop-down list. The options are Export a selected node to a file and Export all nodes to a file.
  • If you are viewing raster metadata, you can click the Edit Metadata button to edit some of the metadata fields as needed. See Edit ENVI Headers for details.

Calibration Metadata

See the Radiometric Calibration topic for a list of sensors from which ENVI automatically reads spectral calibration metadata. Calibration metadata includes additional fields in the header:

  • Radiance Gains: Units are W/(m2 * sr * µm).
  • Radiance Offsets: Units are Units are W/(m2 * sr * µm).
  • Reflectance Gains: No units.
  • Reflectance Offsets: No units.
  • Irradiance: Solar irradiance; units are W/(m2 * µm).
  • Thermal Infrared 1 and Thermal Infrared 2: The K1 and K2 constants used to compute brightness temperatures. For Landsat TM and ETM+, these values are hard-coded from the publication Chander, Markham, and Helder (2009). For Landsat-8, these values are read from the _MTL.txt metadata files.

The following fields are listed under the Image Parameters category:

  • Cloud Cover: Percentage of cloud cover within the image.
  • Sun Azimuth: Angle of the sun (in degrees) from due north in a clockwise direction.
  • Sun Elevation: Angle of the sun (in degrees) above the horizon.

The following fields are listed under the Supplementary category:

  • Earth Sun Distance: ENVI computes the earth-to-sun distance (in Astronomical Units), using the following equation from The Astronomical Almanac for the Year 2013:

    • d = 1.00014 - 0.01671*cos(g) - 0.00014*cos(2g)

    Where:

    g = 357.528 + 0.9856003n

    g is then converted to radiance using the following equation: g = g*(pi/180)

    n = Julian Day - 2451545

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.

Raster Series Metadata

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

  • Regular Bands: A Boolean parameter that indicates if all rasters in a series have the same number of bands and the same band names. For example, this field is set to True if all rasters have three bands representing 400 nm, 500 nm, and 600 nm each. If it is False, the rasters in the series may differ by the number of bands or have different band names, making it more difficult to visually compare the images over time.
  • Regular Grid: A Boolean parameter that indicates whether or not all rasters in a series can be represented on a grid with a common spatial extent, pixel size, and coordinate system. If this field is set to False, each raster may have a different spatial extent or dimensions.

See Also

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