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  >  Docs Center  >  ENVI API  >  Processing  >  ENVIMaximumLikelihoodClassificationTask

ENVIMaximumLikelihoodClassificationTask

ENVIMaximumLikelihoodClassificationTask

This task performs a Maximum Likelihood supervised classification. Maximum Likelihood assumes that the statistics for each class in each band are normally distributed and calculates the probability that a given pixel belongs to a specific class. Each pixel is assigned to the class that has the highest probability.

Example


; Start the application
e = ENVI()
 
; Open an input file
File1 = Filepath('qb_boulder_msi', Subdir=['data'], $
  Root_Dir=e.Root_Dir)
Raster = e.OpenRaster(File1)
 
File2 = Filepath('qb_boulder_msi_vectors.shp', Subdir=['data'], $
  Root_Dir=e.Root_Dir)
Vector = e.OpenVector(File2)
 
; Get training statistics
StatTask = ENVITask('TrainingClassificationStatistics')
StatTask.INPUT_RASTER = Raster
StatTask.INPUT_VECTOR = Vector
StatTask.Execute
 
; Get the task from the catalog of ENVITasks
Task = ENVITask('MaximumLikelihoodClassification')
 
; Define inputs
Task.INPUT_RASTER = Raster
Task.COVARIANCE = StatTask.Covariance
Task.MEAN = StatTask.Mean
 
; Define outputs
Task.OUTPUT_RASTER_URI = e.GetTemporaryFilename()
 
; 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
View1 = e.GetView()
Layer1 = View1.CreateLayer(Task.Output_Raster)

Syntax


Result = ENVITask('MaximumLikelihoodClassification')

Input properties (Set, Get): CLASS_COLORS, CLASS_NAMES, COVARIANCE, INPUT_RASTER, MEAN, OUTPUT_RASTER_URI, OUTPUT_RULE_RASTER_URI, THRESHOLD_PROBABILITY

Output properties (Get only): OUTPUT_RASTER, OUTPUT_RULE_RASTER

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

Methods


This task inherits the following methods from ENVITask:

AddParameter

Execute

Parameter

ParameterNames

RemoveParameter

Properties


This task inherits the following properties from ENVITask:

COMMUTE_ON_DOWNSAMPLE

COMMUTE_ON_SUBSET

DESCRIPTION

DISPLAY_NAME

NAME

REVISION

TAGS

This task also contains the following properties:

CLASS_COLORS (optional)

This is an array of RGB triplets representing the class colors as defined by the input vector.

CLASS_NAMES (optional)

This is a string array of class names as defined by the input vector.

COVARIANCE (required)

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

INPUT_RASTER (required)

Specify a raster on which to perform supervised classification.

MEAN (required)

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

OUTPUT_RASTER

This is a reference to the output raster of filetype ENVI.

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 property, or set it to an exclamation symbol (!), a temporary file will be created.

OUTPUT_RULE_RASTER

This is a reference to the output rule image of filetype ENVI.

OUTPUT_RULE_RASTER_URI (optional)

Specify a string with the fully qualified filename and path of the associated OUTPUT_RASTER. If you do not specify this property, the associated OUTPUT_RASTER will not be created. To force the creation of a temporary file set the property to an exclamation symbol (!).

THRESHOLD_PROBABILITY (optional)

Enter a scalar value for all classes or array of values, one per class, from 0 to and 1. For arrays, the number of elements must equal the number of classes. Pixels with a value lower than the threshold will not be classified. The default value is 0.00000000. The threshold is a probability minimum for inclusion in a class. For example, a value of 0.9 will include fewer pixels in a class than a value of 0.5 because a 90 percent probability requirement is more strict than allowing a pixel in a class based on a chance of 50 percent.

Version History


ENVI 5.2

Introduced

API Version


3.2

See Also


ENVITask, ENVITask::Parameter, ENVISubsetRaster



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