Use the Quick Mosaic tool to create a virtual mosaic of georeferenced rasters.

For advanced mosaicking methods such as color balancing and edge feathering, please use the Seamless Mosaic workflow.

Two options are provided for creating a virtual mosaic:

  • A right-click option in the Layer Manager that lets you group and replace a number of rasters displayed in a view into a virtual mosaic
  • A tool in the ENVI Toolbox that lets you do the same with any number of rasters currently open in ENVI

A virtual raster is an ENVI raster that does not require saving pixel values to a new file. The data of a virtual mosaic raster comes directly from the individual raster components that make up the mosaic.

Option 1: Group Rasters in the Current View

  1. Open and display multiple overlapping (or adjacent) georeferenced rasters in ENVI.
  2. Right-click on the View layer in the Layer Manager and select Quick Mosaic. The Quick Mosaic dialog appears.
  3. The Input Rasters field lists the individual rasters. They are all selected by default. If you do not want to group all of the rasters, use the Ctrl or Shift key on your keyboard to select individual rasters.

    4. Note: The relative order of the rasters listed here will reflect the order in which they are displayed in the view. You can drag and drop rasters in the Layer Manager to modify their relative position before invoking the Quick Mosaic dialog.

  4. Optional: If the input rasters have borders around them, enter the values of the border pixels in the Data Ignore Value field. Those pixels will become transparent in the virtual mosaic.
  5. Optional: Enter a Mosaic Name. If you do not specify a name, ENVI will assign a default name of "Mosaic_" with a date and time stamp.
  6. By default, the input rasters will be removed from the Layer Manager when the virtual mosaic is created. To disable this, set the Remove Layers option to No.
  7. Click OK. The virtual mosaic is displayed in the current view.

Option 2: Use the Quick Mosaic Tool

  1. In the ENVI Toolbox, select Mosaicking > Quick Mosaic. The Quick Mosaic dialog appears.
  2. Click the Browse button next to Input Rasters. Select the georeferenced rasters that you want to mosaic, and click Open.

    3. Note: You can drag and drop entries in the Input Rasters list as needed to determine their relative order in the output mosaic.

  3. Optional: If the input rasters have borders around them, enter the values of the border pixels in the Data Ignore Value field. Those pixels will become transparent in the mosaic.

  4. To write the output to disk, select the File radio button and specify a filename and location. To produce output in memory only, select the Virtual radio button.

  5. Enable the Display result check box to display the output in the view when processing is complete. Otherwise, if the check box is disabled, the result can be loaded from the Data Manager.

  6. To reuse these task settings in future ENVI sessions, save them to a file. Click the down arrow and select Save Parameter Values, then specify the location and filename to save to. Note that some parameter types, such as rasters, vectors, and ROIs, will not be saved with the file. To apply the saved task settings, click the down arrow and select Restore Parameter Values, then select the file where you previously stored your settings.

  7. To run the process in the background, click the down arrow and select Run Task in the Background. If an ENVI Server has been set up on the network, the Run Task on remote ENVI Server name is also available. The ENVI Server Job Console will show the progress of the job and will provide a link to display the result when processing is complete. See ENVI Servers for more information.

  8. Click OK.

See Also

Create Seamless Mosaics, Create Pixel-Based Mosaics