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ENVICalibrateRaster

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 ENVIRadiometricCalibrationTask.

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, Service Pack 2

Introduced

ENVI 5.4

Added Dehydrate and Hydrate methods; added NAME keyword

ENVI 5.5

Added DATA_TYPE keyword

API Version


3.3

See Also


ENVIRaster, ENVIRadiometricCalibrationTask



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