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	Length	Value range
Input Data Set *	String	1 -
Spectral Library *	String	1 -
Spectrum Record Number	Integer	0 - 1	Default: 1
Radiometric Transformation Level	Integer	0 - 1
Radiometric Transformation Component	String	4 - 1	GAIN | OFFSET Default: GAIN
Radiometric Transformation Output Quantity	String	0 - 1	ADJ | RAD | REF Default: ADJ
Exponent	Float	0 - 1	Default: 1
Multiplication Factor	Float	0 - 1	Default: 1

* Required parameter

Parameter descriptions

Input Data Set

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

Spectral Library

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

Spectrum Record Number

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.

Radiometric Transformation Level

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.

Radiometric Transformation Component

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

Radiometric Transformation Output Quantity

Specifies the quantity represented by the radiometric transformation output.

Exponent

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.

Multiplication Factor

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.

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