Use the Relative Water Depth tool to calculates a product depicting relative water depths for water regions from a multispectral raster with at least blue, green, and near infrared bands. The calculation is based on a bottom albedo-independent Bathymetry algorithm developed by Stumpf and Holderied (2003). The bottom albedo-independent nature of the algorithm means that sea floor covered with dark sea grass or bright sand is shown to be at the same depth when they are at the same depth.

You can also write a script to do calculate relative water depth using the CalculateRelativeWaterDepth task.

To calculate relative water depths:

  1. From the Toolbox, select Spectral > Relative Water Depth. The Relative Water Depth dialog appears.
  2. Select an input raster, perform optional spatial and spectral subsetting and/or masking, then click OK.
  3. Select a filter from the Median Filter drop-down list. The default is 3x3, which removes high-frequency noise that often occurs in the water depth results. You can select a different kernel size from the drop-down, or select None to turn filtering off. Setting the median filter to larger sizes creates smoother results, but may smooth over small submerged features.
  4. Enter a filename and location for the Output Raster.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Click OK.

See Also

Spectral Tools