SP2RT

Description

SP2RT reads one spectrum from any type of GDB-supported file as a spectral library file, and uses the spectrum measurement values to evaluate the gains or offsets of a multiband radiometric transformation that is part of an image data set's metadata.

Parameters

Name	Type	Caption	Length	Value range
FILE *	String	Input file name	1 - 192
SPECFILE *	String	Spectral library file name	1 - 192
SPREC	Integer	Spectrum record number	0 - 1	Default: 1
RTLEVEL	Integer	Radiometric transformation level	0 - 1
RTCOMP *	String	Radiometric transformation component	4 - 6	GAIN | OFFSET Default: GAIN
RTQUANT	String	Radiometric transformation output quantity	0 - 3	ADJ | RAD | REF Default: ADJ
EXPONEN	Float	Exponent	0 - 1	Default: 1
MFACTOR	Float	Multiplication factor	0 - 1	Default: 1
MONITOR	String	Monitor mode	0 - 3	ON, OFF Default: ON

* Required parameter

Parameter descriptions

FILE

Specifies the name of the file that contains the image data set to receive the radiometric transformation.

SPECFILE

Specifies the spectral library file that contains the spectrum with which to evaluate the gain or offset component of a multiband radiometric transformation.

SPREC

Specifies the number of the spectrum in the input spectral library with which to evaluate the gain or offset component of a multiband radiometric transformation. If this parameter is not specified, the defaults value of 1 is used, specifying the number of the first spectrum record in the file.

RTLEVEL

Specifies whether to create and add a new radiometric transformation to the end of the existing transformation sequence, or to modify an existing transformation in the sequence.

The specified value must be greater than zero.

RTCOMP

Specifies which component of the specified radiometric transformation (RTLEVEL) to calculate.

RTQUANT

Specifies the quantity represented by the radiometric transformation output.

EXPONEN

Specifies the power to which all spectrum measurement values are to be raised before using the measurements to calculate gain or offset. If this parameter is not specified, the default value of 1 is used.

MFACTOR

Specifies the factor by which all spectrum measurement values are to be multiplied (after the application of the specified exponent (EXPONEN)) before using the measurements to calculate gain or offset. If this parameter is not specified, the default value of 1 is used.

MONITOR

The program progress can be monitored by printing the percentage of processing completed. A system parameter, MONITOR, controls this activity.

Available options are:

• ON: Turns the monitor ON (default)
• OFF: Turns the monitor OFF (recommended if running in batch or background mode)

Details

Each spectrum measurement value for which the wavelength coordinate matches the center wavelength of a data set band (that is, 'corresponds' to a data set band) is used to calculate a radiometric transformation gain or offset for that band, depending on the user specification. Spectrum measurement values are not required to correspond to a data set band, nor are all data set bands required to correspond to a spectrum measurement value.

The radiometric transformation gain or offset for a data set band that has no corresponding spectrum measurement value is evaluated to 1.0 or 0.0, respectively.

Two separate applications of this program are required to define a single radiometric transformation with both a gain and an offset component. If the first application creates a new transformation (default value for RTLEVEL), RTLEVEL must be explictly set in the second application to the level of the new transformation. An appropriate value for RTQUANT (Radiometric Transformation Output Quantity) for the first application (partial definition of the transformation) is ADJ.

A gain or offset value for a band with a corresponding measurement value m is evaluated to:

mfactor * m^exponen

Example

This example demonstrates the use of SP2RT to create a flat spectrum transformation for cuprad.pix.

Create a radiometric transformation for cuprad.pix from the mean flat image-derived spectrum. This transformation will be added to the end of the existing sequence.

EASI>file	=	"cuprad.pix"	! input file
EASI>specfile	=	"mean.spl"	! input spectral library
EASI>sprec	=		! use first spectrum record in mean.spl
EASI>rtlevel	=		! default, create new RT
EASI>rtcomp	=	"gain"	! evaluate gain component of the new RT
EASI>rtquant	=	"adj"	! non-physical adjustment
EASI>exponen	=	-1	! reciprocal of spectrum values used as gains
EASI>mfactor	=		! default, no multiplication factor

EASI>run SP2RT