Use Buffer Zone Image to create a buffer zone image from a classified image. In the buffer zone image every pixel has a floating-point or integer value that is defined as the distance from that pixel to the nearest pixel of the selected class or classes in units of pixels. You designate a maximum distance value and the result is that any pixels with a distance larger than that value will be set to the maximum distance value.

You can also write a script to create buffer zone images using the BufferZone task.

  1. From the Toolbox, select Classification > Post Classification > Buffer Zone Image. The Classification Input File dialog appears.
  2. Select the input classification file and any optional spatial subsetting, then click OK. The Buffer Zone dialog appears.
  3. From the Class Names list, select the classs to measure the distance to. If more than one class is selected, the distance will be from the pixel to the nearest class.
  4. From the Output Data Type drop-down list, select Integer or Float.
  5. Click the Maximum Distance increase/decrease buttons to set the maximum distance to measure, or type the value (in pixels) into the corresponding field. Any pixels with a distance larger than this value will be set to the maximum distance value.
  6. Select an output filename and folder in the Output Raster field.
  7. Enable the Preview check box to see a preview of the settings before you click OK to process the data. The preview is calculated only on the area in the view and uses the resolution level at which you are viewing the image. See Preview for details on the results. To preview a different area in your image, pan and zoom to the area of interest and re-enable the Preview option.

  8. 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.

  9. 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.

  10. 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.

  11. Click OK.