View and Edit Metadata

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Lesson content

Lesson 1 of 1

View and Edit Metadata

In this quick guide, you will:

•

Open and display an aerial orthophoto. * •

View basic and detailed metadata. * •

Use the Edit ENVI Header tool to edit the image description.

Sample Data

Download sample data below. Then extract the contents of the .zip file to a local directory.

[GettingStarted.zip

116 MB

DownloadArrow down with horizontal line beneath it](assets/GettingStarted.zip)

1

Open ENVI. 2. 2

Click the Open button in the Toolbar. The Toolbar is located along the top of the ENVI application.

3

When the Open dialog appears, navigate to the location where you saved the sample data. Select CentralParkOrthophoto.dat and click Open. The center of the image is displayed at full (100%) resolution in the view. 2. 4

Look at the Property Sheet in the lower-right corner of the ENVI application. It shows basic properties of the raster such as its dataset name, description, dimensions, and more.

5

In the Layer Manager, right-click on CentralParkOrthophoto.dat layer and select View Metadata. The View Metadata dialog appears. Here you can view the full set of metadata for the orthophoto. The Raster tag shows most of the same metadata as the Property Sheet.

Metadata are stored in an ENVI header file (.hdr). The header file has the same root name, and resides in the same directory, as the raster file.

6

Click the Extents tag on the left side of the View Metadata dialog. This tag shows the UTM map coordinates of the four corners of the image, along with the units of the map projection. Next, you will add two new fields to the metadata. 2. 7

Click the Edit Metadata button in the View Metadata dialog. The Edit ENVI Header dialog appears. Here you can see the metadata fields and their values.

8

Click the Spectral tab. The Wavelength field lists the band names and their associated center wavelengths. The original image downloaded from the U.S. Geological Survey (USGS) EarthExplorer(opens in a new tab) site did not contain wavelength metadata, only band names. We used the Edit ENVI Header tool to add the peak wavelengths you see here. For the near-infrared band, we used the center wavelength (840 nm).

9

Click the Main tab and notice that the Description field already contains some text. 2. 10

Change the description to "USGS High Resolution Orthophoto; Central Park," omitting the date and resolution. 3. 11

Click OK to dismiss the Edit ENVI Header dialog. The image closes and reopens while the associated header file (CentralParkOrthophoto.hdr) is updated with the new metadata.

The header file must be in a directory with write permissions, or else you will receive an error upon clicking OK.

12

Look at the Property Sheet and notice the revised description.

This concludes the exercise.

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