CalculateRelativeWaterDepth Task

This task 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.

The water depth results are relative since they do not depict absolute depths (the results are scaled from zero to one). The intent of these results is to provide a general feel for the Bathymetry; they are not to be used for navigational purposes.

Example

; Start the application

e = ENVI()

; Open an input file

File = Filepath('qb_boulder_msi', Subdir=['data'], $

  Root_Dir=e.Root_Dir)

Raster = e.OpenRaster(File)

; Get the task from the catalog of ENVITasks

Task=ENVITask('CalculateRelativeWaterDepth')

; Define inputs

Task.INPUT_RASTER = Raster

; Run the task

Task.Execute

; Get the collection of data objects currently available in the Data Manager

DataColl = e.Data

; Add the output to the Data Manager

DataColl.Add, Task.OUTPUT_RASTER

; Display the result

View = e.GetView()

Layer = View.CreateLayer(Task.OUTPUT_RASTER)

Syntax

Result = ENVITask('ENVICalculateRelativeWaterDepth')

Input parameters (Set, Get): INPUT_RASTER, MEDIAN_FILTER, OUTPUT_RASTER_URI

Output parameters (Get only): OUTPUT_RASTER

Parameters marked as "Set" are those that you can set to specific values. You can also retrieve their current values any time. Parameters marked as "Get" are those whose values you can retrieve but not set.

Input Parameters

INPUT_RASTER (required)

Specify a raster which has at least blue, green, and near infrared bands.

MEDIAN_FILTER (optional)

The default filter setting is 3x3, which removes high-frequency noise that often occurs in the water depth results. You can specify a different kernel size for the filter, or 'None' to turn filtering off. Setting the median filter to larger sizes creates smoother results, but may smooth over small submerged features.

OUTPUT_RASTER_URI (optional)

Specify a string with the fully qualified filename and path of the associated OUTPUT_RASTER.

If you do not specify this parameter, or set it to an exclamation symbol (!), ENVI creates a temporary file.
If you set it to the hash symbol (#), ENVI creates a file in the temporary directory, but this file will not be deleted when ENVI closes.