QUAC Task

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.

The virtual raster associated with this task is ENVIQUACRaster.

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'

; 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 ('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:

Properties

This task inherits the following properties from ENVITask:

COMMUTE_ON_DOWNSAMPLE

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

4.2