ENVIQUACRaster

This function constructs an ENVIRaster from a source raster that has QUick Atmospheric Correction (QUAC) applied. It requires a separate license for the ENVI Atmospheric Correction Module; contact your sales representative for more information.

The result is a virtual raster, which has some additional considerations with regard to methods and properties. See Virtual Rasters for more information, including how they differ from ENVITasks.

The equivalent task is QUAC.

The output raster consists of unsigned 2-byte integer reflectance data, scaled by 10,000. If you export the raster to disk, the data ignore value is set to 0 in the corresponding header file. You can override this value by setting the DATA_IGNORE_VALUE keyword in the ENVIRaster::Export method. Any bad bands are automatically found and set accordingly.

Example

; Start the application

e = ENVI()

; Open an input file

file = FILEPATH('qb_boulder_msi', ROOT_DIR=e.ROOT_DIR, $

SUBDIRECTORY = ['data'])

raster = e.OpenRaster(file)

; create QUAC raster

QUACImage = ENVIQUACRaster(raster)

; save it in ENVI raster format

newFile = e.GetTemporaryFilename()

QUACImage.Export, newFile, 'ENVI'

; Open the QUAC image

QUACImage = e.OpenRaster(newFile)

; Display the result

View = e.GetView()

Layer = View.CreateLayer(QUACImage)

Syntax

Result = ENVIQUACRaster(Input_Raster [, Keywords=value])

Return Value

This routine returns a reference to an ENVIRaster.

Arguments

Input_Raster

Specify the input ENVIRaster.

Methods

This virtual raster inherits methods and properties from ENVIRaster; however the following methods will override the ENVIRaster methods:

Dehydrate

Hydrate

Keywords

ERROR (optional)

Set this keyword to a named variable that will contain any error message issued during execution of this routine. If no error occurs, the ERROR variable will be set to a null string (''). If an error occurs and the routine is a function, then the function result will be undefined.

When this keyword is not set and an error occurs, ENVI returns to the caller and execution halts. In this case, the error message is contained within !ERROR_STATE and can be caught using IDL's CATCH routine. See IDL Help for more information on !ERROR_STATE and CATCH.

See Manage Errors for more information on error handling in ENVI programming.

NAME

Specify a string that identifies the raster.

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 option, 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 5.3	Introduced
ENVI 5.3.1	Documented the dehydrated form of this virtual raster
ENVI 5.4	Added Dehydrate and Hydrate methods; added NAME keyword

API Version

4.2