Internal: ENVI: Do You Know Your Data?

Help Article Update 2

So you have downloaded some imagery from a data provider for project and you want to view it in ENVI. However, for some strange reason the ENVI Header dialog displays asking for some image dimensions and so forth. What’s wrong you ask yourself. You chose the ENVI file format, *.dat , from the choice for available formats. What you missed in this case was the associated *.hdr or header file ENVI needs to open the image.

What this demonstrates is the need to know the contents of the files you are downloading, and if you have all the necessary files for your workflow. You may not know what is required but it is worthwhile to do some research or ask an experienced user what is needed. A few minutes of studying the ENVI Help specific to your workflow could prevent potential hours of frustration dealing with error messages or unexpected results.

The following excerpt from the ENVI Classic Help demonstrates how many files may be needed for this particular imagery.  Notice both are GeoTiff files but the later files have associated ‘metadata’ files that can be used to calibrate the imagery

File > Open External File > Landsat

GeoTIFF: Reads Landsat GeoTIFF Select a *.TIF file.

* Note this is a fairly straightforward choice, just one file.

 

GeoTIFF with Metadata: Reads Landsat MSS Multispectral Sensor; a Landsat sensor., TM and ETM+ metadata files from the Global Land Cover Facility (GLCF) or from the U.S. Geological Survey (USGS). The metadata files provide information needed to open the associated imagery.

Landsat Metadata dialog

For GLCF Landsat data , select a *.met file

For USGS Landsat data select a *.txt file

 For Landsat Level-1 Product Generation System (LPGS), select a *.mtl file

Notice that in these cases you will need to download the *.tif file and its associated metadata file.