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  >  Docs Center  >  ENVI API  >  Processing  >  ENVISpectralIndexTask

ENVISpectralIndexTask

ENVISpectralIndexTask

This task creates a spectral index raster from one pre-defined spectral index. Spectral indices are combinations of surface reflectance at two or more wavelengths that indicate relative abundance of features of interest.

See ENVISpectralIndicesTask to create a raster with one or more bands, where each band represents a different spectral index.

The data-ignore value of the output raster is set to -1034.

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)
 
; Process a spatial subset
Subset = ENVISubsetRaster(Raster, Sub_Rect=[600,200,799,399])
 
; Get the task from the catalog of ENVITasks
Task=ENVITask('SpectralIndex')
 
; Define inputs
Task.INDEX = 'Normalized Difference Vegetation Index'
Task.INPUT_RASTER = Subset
 
; 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('SpectralIndex')

Input properties (Set, Get): INDEX, INPUT_RASTER, OUTPUT_RASTER_URI

Output properties (Get only): OUTPUT_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:

INDEX (required)

Specify a string representing the pre-defined spectral index to apply to the input raster:

Anthocyanin Reflectance Index 1

Anthocyanin Reflectance Index 2

Atmospherically Resistant Vegetation Index

Burn Area Index

Carotenoid Reflectance Index 1

Carotenoid Reflectance Index 2

Cellulose Absorption Index

Clay Minerals

Difference Vegetation Index

Enhanced Vegetation Index

Ferrous Minerals

Global Environmental Monitoring Index

Green Atmospherically Resistant Index

Green Chlorophyll Index

Green Difference Vegetation Index

Green Leaf Index

Green Normalized Difference Vegetation Index

Green Optimized Soil Adjusted Vegetation Index

Green Ratio Vegetation Index

Green Soil Adjusted Vegetation Index

Green Vegetation Index

Infrared Percentage Vegetation Index

Iron Oxide

Leaf Area Index

Lignin Cellulose Absorption Index

Modified Chlorophyll Absorption Ratio Index

Modified Chlorophyll Absorption Ratio Index - Improved

Modified Non-Linear Index

Modified Normalized Difference Water Index

Modified Red Edge Normalized Difference Vegetation Index

Modified Red Edge Simple Ratio

Modified Simple Ratio

Modified Soil Adjusted Vegetation Index 2

Modified Triangular Vegetation Index

Modified Triangular Vegetation Index - Improved

Moisture Stress Index

Non-Linear Index

Normalized Burn Ratio

Normalized Burn Ratio Thermal 1

Normalized Difference Built-Up Index

Normalized Difference Infrared Index

Normalized Difference Lignin Index

Normalized Difference Mud Index

Normalized Difference Nitrogen Index

Normalized Difference Snow Index

Normalized Difference Vegetation Index

Normalized Difference Water Index

Normalized Multiband Drought Index

Optimized Soil Adjusted Vegetation Index

Photochemical Reflectance Index

Plant Senescence Reflectance Index

Red Edge Normalized Difference Vegetation Index

Red Edge Position Index

Red Green Ratio Index

Renormalized Difference Vegetation Index

Simple Ratio

Soil Adjusted Vegetation Index

Structure Insensitive Pigment Index

Sum Green Index

Transformed Chlorophyll Absorption Reflectance Index

Transformed Difference Vegetation Index

Triangular Greenness Index

Triangular Vegetation Index

Visible Atmospherically Resistant Index

Vogelmann Red Edge Index 1

Vogelmann Red Edge Index 2

Water Band Index

Wide Dynamic Range Vegetation Index

WorldView Built-Up Index

WorldView Improved Vegetative Index

WorldView New Iron Index

WorldView Non-Homogeneous Feature Difference

WorldView Soil Index

WorldView Water Index

INPUT_RASTER (required)

Specify a raster from which to generate a spectral index raster.

OUTPUT_RASTER

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

The data ignore value is set to -10 34.

OUTPUT_RASTER_URI (optional)

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

  • If you set this property to an asterisk symbol (*), the output raster will be virtual and not written to disk.
  • If you do not specify this property, or set it to an exclamation symbol (!), a temporary file will be created.

Version History


ENVI 5.2

Introduced

ENVI 5.5

OUTPUT_RASTER_URI now supports '*', which allows OUTPUT_RASTER to be virtual output.

API Version


3.2

See Also


ENVITask, ENVITask::Parameter, ENVISpectralIndicesTask, ENVISpectralIndexRaster, ENVIQuerySpectralIndicesTask, ENVISubsetRaster



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