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ISIS 3 Application Documentation

clemnircal

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Performs radiometric corrections on Clementine NIR images

Overview Parameters Example 1

Description

INTRODUCTION

This program performs radiometric corrections to images acquired by the Clementine spacecraft Near Infrared camera and writes the output image values in units of radiance.

EQUATIONS

Term1 = ( DR(x,y) - digital_offset ) / Gfact(gm)
Term2 = Term1 - bias_global - BIAS(x,y) - (om * V)
Term3 = Term2 / t
Term4 = Term3 - DC(x,y) - 0.730
Term5 = Term4 - therm - thermShape
Term6 = Term5 / FF(x,y)
Term7 = Term6 / OF(x,y)
Term8 = Term7 - AF(x,y)
R(x,y) = Term8 * abscoef

General equations applied to data for radiometric correction are indicated below:

Let: x,y = line and sample position of pixel in an image
R(x,y) = Result of correction in absolute radiance.
DO(x,y) = Result of correction. The output can either be absolute radiance values or they can be converted to reflectance(I/F values
DR(x,y) = Raw input density number
FF(x,y) = Flat-field as a function of filter and line, sample
position. This will be read from an ISIS cube file.
OF(x,y) = Orbit dependent flat file correction.
DC(x,y) = Dark current as a function of compression type,
line, sample position. AF(x,y) = Empirical additive flat-field coefficients at line, sample position.
BIAS(x,y) = Bias correction as a function of compression type, line, sample position.
digital_offset = 9.0
bias_global = 2.0
V = -.91
abscoef = 1.0
g(GainModeID) = Gain factor as a function of insturment GainModeID
g(0) = 2.0235
g(1) = 8.2755
g(2) = 4.9144
g(5) = 0.9443
g(8) = 4.1835
g(9) = 1.3530
g(11) = 15.9844
g(13) = 7.77177
g(16) = 28.1618
g(17) = 24.8658
g(18) = 21.9100
g(19) = 18.6140
g(22) = 6.83130
g(23) = 3.48425
g(24) = 20.3218
g(25) = 17.9433
g(26) = 15.8104
g(27) = 13.4320
g(28) = 9.32361
g(29) = 6.95951
g(30) = 4.75472
g(31) = 2.43896
g(33) = 13.9238
g(34) = 12.2687
g(36) = 7.23501
g(41) = 7.04438
g(42) = 6.16495
g(44) = 3.57405
g(45) = 2.73995
g(46) = 1.88595
g(48) = 11.9078
g(50) = 9.26433
g(52) = 5.39513
g(53) = 4.08125
g(61) = 1.40899
g(62) = 0.964975
gm = Gain_mode of instrument(gm = 1,2,4)
om = Offset_mode of instrument(om = 1,2,3,4,...,31)
t = Optimal integration duration of observation in seconds (function of ExposureDuration on labels in milliseconds.)
therm = Thermal background correction value
thermShape = Thermal shape correction value (always 0.0)

Categories

Related Objects and Documents

Applications

History

Tracie Sucharski1994-11-28 Original Version (nircal.F)
Steven Lambright & Steven Koechle2007-05-16 Converted to Isis 3.0
Steven Koechle2007-06-11 Removed unused Thermal Shape Correction Parameter. Fixed table lookup problem, and Radiometry group
Steven Lambright2007-06-14 Fixed bugs in XML file, added an example, added more data to Radiometry group.
Christopher Austin2007-02-20 Altered the output cube's BandBin group, changing the Keyword "Name" back to "FilterName".
Steven Lambright2008-05-13 Removed references to CubeInfo

Parameter Groups

Files

Name Description
FROM Input file name
TO Output file name
FFFILE Array of flat-field coefficients
OFFILE Array of orbit dependent flat-field coefficients
AFFILE Array of empirical additive flat-field coefficients
DCFILE Dark current file
BIASFILE Bias correction file
BPFILE Bad pixel file

Settings

Name Description
BPFLAG Convert bad pixels to null
THCOR Apply thermal background correction
ABSCOEF Absolute coefficient
HISAT High saturation value
X

Files: FROM

Description

Specify the input file to be corrected.

Type cube
File Mode input
Filter *.cub
Close Window
X

Files: TO

Description

Specify the output file. The result will be the radiometrically corrected image.

Type cube
File Mode output
Pixel Type real
Filter *.cub
Close Window
X

Files: FFFILE

Description

This parameter allows the user to use an alternate flat-field file. In most cases, the default should be used for this parameter to indicate the derived flat-field file is to be used.

Type cube
File Mode input
Internal Default Automatic
Filter *.cub
Close Window
X

Files: OFFILE

Description

The parameter allows the user to use an alternate orbit dependent flat-field file. In most cases, the default should be used for this paramter.

Type cube
File Mode input
Internal Default Automatic
Filter *.cub
Close Window
X

Files: AFFILE

Description

The parameter allows the user to use an alternate emperical additive flat-field file. In most cases, the default should be used for this parameter.

Type cube
File Mode input
Internal Default Automatic
Filter *.cub
Close Window
X

Files: DCFILE

Description

This parameter allows the user to use an alternate dark current file. In most cases, the default should be used for this parameter to indicate the derived dark file is to be used. The name of the derived dark current file is "$ISIS3DATA/clementine1/calibration/nir/dark_nir.cub" When InstrumentCompressionType = "CLEM-JPEG-0" the name of the derived dark current file is "$ISIS3DATA/clementine1/calibration/nir/dark_nir_cmp0.cub"

Type cube
File Mode input
Internal Default Automatic
Filter *.cub
Close Window
X

Files: BIASFILE

Description

This parameter allows the user to use an alternate bias file. In most cases, the default should be used for this parameter to indicate the derived bias file is to be used. The name of the derived bias file is "$ISIS3DATA/clementine1/calibration/nir/bias_nir.cub" When InstrumentCompressionType = "CLEM-JPEG-0" the name of the derived bias file is "$ISIS3DATA/clementine1/calibration/nir/bias_nir_cmp0.cub"

Type cube
File Mode input
Internal Default Automatic
Filter *.cub
Close Window
X

Files: BPFILE

Description

This parameter allows the user to use an alternate bad pixel file. In most cases, the default should be used for this parameter to indicate the derived bad pixel file is to be used. The name of the derived bad pixel file is "$ISIS3DATA/clementine1/calibration/nir/badpix_nir.v3.cub" When InstrumentCompressionType = "CLEM-JPEG-0" the name of the derived bad pixel file is "$ISIS3DATA/clementine1/calibration/nir/badpix_nir_cmp0.v3.cub"

Type cube
File Mode input
Internal Default Automatic
Filter *.cub
Close Window
X

Settings: BPFLAG

Description

This option allows the user to decide whether to keep or remove known bad pixels. When enabled, DN values of 0.0 in the bad pixel cube are known bad pixels that will be set to NULL in the output.

Type boolean
Default true
Close Window
X

Settings: THCOR

Description

Apply thermal background correction

Type boolean
Default true
Close Window
X

Settings: ABSCOEF

Description

Absolute coefficient

Type double
Default 1.0
Close Window
X

Settings: HISAT

Description

DN values greater than this value in the input cube will be set to HRS.

Type double
Default 240.0
Close Window

Example 1

Calibrating a cube to radiance values using nircal

Description

Calibrating a cube to radiance values using nircal

Command Line

clemnircal nircal FROM=lna3056k.cub TO=lna3056k.cal.cub
In this example nircal will calibrate lna3056k.cub.

GUI Screenshot

Calibrate clemnircal.cub

Calibrate lna3056k.cub

In this example clemnircal will calibrate lna3056k.cub using the defaults.

Input Image

lna3056k.cub before being corrected

Image before correction

Parameter Name: FROM

This is the input image lna3056k.cub before being corrected with clemnircal.

Output Image

lna3056k.cub after being corrected

Image after correction

Parameter Name: TO

This is the input image lna3056k.cub after being corrected with clemnircal. There are scattered NULL pixels because BPFLAG was true, so all known bad pixels were automatically set to NULL.