ENVICalibrateRaster

This function constructs an ENVIRaster from a source raster that has been calibrated to radiance, top-of-atmosphere (TOA) reflectance, or brightness temperatures.

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 RadiometricCalibration.

Example

This example calibrates Landsat 8 multispectral bands to TOA reflectance. Replace the example filename with the path and filename of your own Landsat-8 file.

; Start the application

e = ENVI()

; Open a Landsat 8 scene

file = 'LC80410302013213LGN00_MTL.txt'

raster = e.OpenRaster(file)

; Landsat-8 data are stored in a five-element

; array. Multispectral bands from the OLI sensor

; are stored in the first array element.

OLIBands = raster[0]

; Calibrate to TOA reflectance

reflRaster = ENVICalibrateRaster(OLIBands, $

  CALIBRATION='Top-of-Atmosphere Reflectance')

; Display the result

view = e.GetView()

layer = view.CreateLayer(reflRaster)

view.Zoom, /FULL_EXTENT

See More Examples below.

Syntax

ENVIRaster = ENVICalibrateRaster(Input_Raster [, Keywords=value])

Return Value

This routine returns a reference to an ENVIRaster.

Arguments

Input_Raster

Specify an input ENVIRaster. In the case of Landsat or other metaspectral datasets, specify the correct array element corresponding to the band group you are interested in. The code example above shows a Landsat-8 scenario.

Methods

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

Dehydrate

Hydrate

Keywords

CALIBRATION (optional)

Set this keyword to a string indicating the calibration type. The choices are:

Radiance (default)
Top-of-Atmosphere Reflectance
Brightness Temperature

See Radiometric Calibration for the calibration options that are available for different sensors.

DATA_TYPE (optional)

Specify one of the following strings, indicating the output data type:

String	Data Type
byte	Byte (8 bits)
double	Double-precision floating point (64 bits)
float	Floating point (32 bits)
int	Integer (16 bits)
long	Long integer (32 bits)
uint	Unsigned integer (16 bits)
ulong	Unsigned long integer (32 bits)

ERROR

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.

More Examples

Calibrate a WorldView-3 multispectral dataset to radiance

Replace the example filename with the path and filename of your own WorldView-3 file.

; Start the application

e = ENVI()

; Open a WorldView-3 scene

file = '14OCT14083351-M2AS-054127053010_01_P001.TIL'

raster = e.OpenRaster(file)

; Calibrate to radiance

reflRaster = ENVICalibrateRaster(raster, $

  CALIBRATION='Radiance')

; Display the result

view = e.GetView()

layer = view.CreateLayer(reflRaster)

view.Zoom, /FULL_EXTENT

Version History

ENVI 5.3.2	Introduced
ENVI 5.4	Added Dehydrate and Hydrate methods; added NAME keyword
ENVI 5.5	Added DATA_TYPE keyword

API Version

4.3