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QUAC

ENVIQUACTask

This task performs QUick Atmospheric Correction (QUAC®) on multispectral or hyperspectral imagery. If you export the result to disk, the data ignore value is set to 0 in the corresponding header file.

The result consists of unsigned 2-byte integer reflectance data, scaled by 10,000.

This task requires a separate license for the ENVI Atmospheric Correction Module; contact your sales representative for more information.

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 QUAC task from the catalog of ENVITasks
Task = ENVITask('QUAC')
 
; Define inputs
Task.INPUT_RASTER = Raster
Task.SENSOR = 'QuickBird'
 
; 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 ('QUAC')

Input properties (Set, Get): INPUT_RASTER, SENSOR, 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:

INPUT_RASTER (required)

Specify a raster on which to perform the atmospheric correction.

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 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.

SENSOR (optional)

Specify one of the following strings, indicating the sensor type of the input raster:

Generic / Unknown Sensor
Highly Vegetated Scenes
AISA-ES
ALI
ASAS
AVIRIS
CAP ARCHER
CASI
COMPASS
HYCAS
HYDICE
HyMap
Hyperion
Landsat TM/ETM/OLI
LASH
MARS
MODIS
QuickBird
RGB
WorldView-2
Near Infrared (NIR)
Near-Shortwave Infrared (NIR-SWIR)
  • If SENSOR is not set, then the task uses the Generic/Unknown Sensor option to guess the best sensor type, based on the number of input bands and their wavelengths.
  • Select the Highly Vegetated Scenes option if the image is highly vegetated.
  • Select the Near Infrared (NIR) option if the input raster has more than 70 bands and the wavelengths span the near-infrared region.
  • Select the Near-Shortwave Infrared (NIR-SWIR) option if the input raster has more than five bands and the wavelengths span the near-shortwave infrared region.

Version History


ENVI 5.1

Introduced

ENVI 5.3

Updated baseline algorithm

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, ENVICalculateQUACGainOffsetTask, ENVIQUACRaster, ENVIDarkSubtractionCorrectionTask, ENVIFlatFieldCorrectionTask, ENVIIARReflectanceCorrectionTask



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