SpectralInformationDivergenceClassification Task

This task performs the Spectral Information Divergence (SID) classification.

Example

This example performs the following steps:

Opens an AVIRIS hyperspectral image subset.
Runs a forward minimum noise transform (MNF) to reduce noise in the data.
Defines three regions of interest (ROIs), each containing nine pixels of a common material.
Retrieves the spectra from the ROIs and uses their means as targets for Spectral Information Divergence classification.
Runs the SID task, which performs spectral information divergence classification.
Displays the result. To see all of the bands, open the Data Manager.

; Start the application

e = ENVI()

; Open an input file

File = Filepath('AVIRISReflectanceSubset.dat', $

  SUBDIR=['data', 'hyperspectral'], $

  ROOT_DIR=e.Root_Dir)

Raster = e.OpenRaster(File)

; First run a Forward MNF on the data

Task = ENVITask('ForwardMNFTransform')

Task.INPUT_RASTER = Raster

Task.Execute

; Use the first 15 MNF bands to run SID

Subset = ENVISubsetRaster(Task.OUTPUT_RASTER, BANDS=LINDGEN(15))

; Define three ROIs, each containing 9 pixels of a common material.

nSpectra = 9d

roi1 = ENVIROI(NAME='Green Field')

pixelAddr1 = [[77,182],[78,182],[79,182], $

  [77,183],[78,183],[79,183], $

  [77,184],[78,184],[79,184]]

roi1.AddPixels, pixelAddr1, SPATIALREF=Subset.SPATIALREF

roi2 = ENVIROI(NAME='Soil')

pixelAddr2 = [[386,285],[387,285],[388,285], $

  [386,286],[387,286],[388,286], $

  [386,287],[387,287],[388,287]]

roi2.AddPixels, pixelAddr2, SPATIALREF=Subset.SPATIALREF

roi3 = ENVIROI(NAME='Ground')

pixelAddr3 = [[296,326],[297,326],[298,326], $

  [296,327],[297,327],[298,327], $

  [296,328],[297,328],[298,328]]

roi3.AddPixels, pixelAddr3, SPATIALREF=Subset.SPATIALREF

; Retrieve the spectra from the ROIs and use their mean as targets

; for the Spectral Information Divergence (SID) task

spectra1 = Subset.GetData(ROI=roi1)

mean1 = Total(spectra1,1) / nSpectra

spectra2 = Subset.Getdata(ROI=roi2)

mean2 = Total(spectra2,1) / nSpectra

spectra3 = Subset.GetData(ROI=roi3)

mean3 = Total(spectra3,1) / nSpectra

means = [[mean1],[mean2],[mean3]]

; Get the task from the catalog of ENVITasks

Task = ENVITask('SpectralInformationDivergenceClassification')

Task.INPUT_RASTER = Subset

Task.MEAN = means

; Run the task

Task.Execute

; Get the data collection

dataColl = e.Data

; Add the output to the data collection

dataColl.Add, Task.OUTPUT_RASTER

; Display the result

View = e.GetView()

Layer = View.CreateLayer(Task.OUTPUT_RASTER)

Syntax

Result = ENVITask('SpectralInformationDivergenceClassification')

Input parameters (Set, Get): CLASS_COLORS, CLASS_NAMES, INPUT_RASTER, MEAN, OUTPUT_RASTER_URI, OUTPUT_RULE_RASTER_URI, THRESHOLD

Output parameters (Get only): OUTPUT_RASTER, OUTPUT_RULE_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

CLASS_COLORS (optional)

This is an array of [3, number of classes] for RGB triplets representing the class colors.

CLASS_NAMES (optional)

This is an array of [number of classes] for unclassified and class names.

INPUT_RASTER (required)

Specify an input raster to process.

MEAN (required)

Specify an array that is [number of bands, number of classes].

OUTPUT_RASTER_URI (optional)

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

If you do not specify this parameter, the OUTPUT_RASTER will not be created.
If you set this parameter to an asterisk symbol (*), the OUTPUT_RASTER will be virtual and not written to disk.
To force the creation of a temporary file, set this parameter to an exclamation symbol (!).
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.

OUTPUT_RULE_RASTER_URI (optional)

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

If you do not specify this parameter, the OUTPUT_RULE_RASTER will not be created.
To force the creation of a temporary file set the parameter to an exclamation symbol (!).
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.

THRESHOLD (required)

Specify a maximum value or array of maximum values (one for each class) for each class is tested against its corresponding maximum spectral divergence. The default value is 0.05.