clemnircal
Performs radiometric corrections on Clementine NIR images
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)
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 Sucharski | 1994-11-28 | Original Version (nircal.F) |
| Steven Lambright & Steven Koechle | 2007-05-16 | Converted to Isis 3.0 |
| Steven Koechle | 2007-06-11 | Removed unused Thermal Shape Correction Parameter. Fixed table lookup problem, and Radiometry group |
| Steven Lambright | 2007-06-14 | Fixed bugs in XML file, added an example, added more data to Radiometry group. |
| Christopher Austin | 2007-02-20 | Altered the output cube's BandBin group, changing the Keyword "Name" back to "FilterName". |
| Steven Lambright | 2008-05-13 | Removed references to CubeInfo |
Parameters
Files
Specify the input file to be corrected.
| Type | cube |
|---|---|
| File Mode | input |
| Filter | *.cub |
Specify the output file. The result will be the
radiometrically corrected image.
| Type | cube |
|---|---|
| File Mode | output |
| Pixel Type | real |
| Filter | *.cub |
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 |
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 |
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 |
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 "$ISISDATA/clementine1/calibration/nir/dark_nir.cub"
When InstrumentCompressionType = "CLEM-JPEG-0" the name
of the derived dark current file is
"$ISISDATA/clementine1/calibration/nir/dark_nir_cmp0.cub"
| Type | cube |
|---|---|
| File Mode | input |
| Internal Default | Automatic |
| Filter | *.cub |
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 "$ISISDATA/clementine1/calibration/nir/bias_nir.cub"
When InstrumentCompressionType = "CLEM-JPEG-0" the name
of the derived bias file is
"$ISISDATA/clementine1/calibration/nir/bias_nir_cmp0.cub"
| Type | cube |
|---|---|
| File Mode | input |
| Internal Default | Automatic |
| Filter | *.cub |
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 "$ISISDATA/clementine1/calibration/nir/badpix_nir.v3.cub"
When InstrumentCompressionType = "CLEM-JPEG-0" the name
of the derived bad pixel file is
"$ISISDATA/clementine1/calibration/nir/badpix_nir_cmp0.v3.cub"
| Type | cube |
|---|---|
| File Mode | input |
| Internal Default | Automatic |
| Filter | *.cub |
Settings
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 |
Apply thermal background correction
| Type | boolean |
|---|---|
| Default | true |
Absolute coefficient
| Type | double |
|---|---|
| Default | 1.0 |
DN values greater than this value in the input cube will be set to HRS.
| Type | double |
|---|---|
| Default | 240.0 |
Example 1
Calibrating a cube to radiance values using nircal
Calibrating a cube to radiance values using nircal
Command Line
In this example nircal will calibrate lna3056k.cub.
clemnircal
nircal FROM=lna3056k.cub TO=lna3056k.cal.cub
GUI Screenshot
Calibrate lna3056k.cub
Calibrate clemnircal.cubIn this example clemnircal will calibrate lna3056k.cub using the defaults.
Input Image
Image before correction
lna3056k.cub before being corrected
Parameter Name:
FROM
This is the input image lna3056k.cub before being corrected with clemnircal.
Output Image
Image after correction
lna3056k.cub after being corrected
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.