RLUTSP

Description

Extracts radiance spectra from a radiance lookup table (RLUT) according to user-specified table dimension intervals and outputs them to a file. The user also specifies whether to extract spectra for LG, the at-sensor radiance reflected by the target, or LO, the at-sensor radiance from all other sources.

Parameters

rlutsp(rlutfili, dbsrl, specfilo, filotype, rstype, reflint, razint, vzaint, szaint, vwvcint, aodint, smrint, elevint, saltint)

Name	Type	Caption	Length	Value range
RLUTFILI*	str	Input radiance LUT file name	1 -
DBSRL*	List[int]	Input at-sensor radiance LUT segment	1 - 1
SPECFILO*	str	Output spectral library file name	1 -
FILOTYPE	str	Output spectral library format	0 -	SPCB|XLS|TXT Default: SPCB
RSTYPE	str	Radiance spectrum type	0 - 2	LG | LO Default: LG
REFLINT*	List[float]	Reflectance interval	2 - 2	1.0,1.0
RAZINT*	List[float]	Relative view-solar azimuth interval	2 - 2	360.0,360.0
VZAINT*	List[float]	View zenith angle interval	2 - 2	180.0,180.0
SZAINT*	List[float]	Solar zenith angle interval	2 - 2	90.0,90.0
VWVCINT	List[float]	Atmospheric water vapor content interval	0 - 2	Default: 0.0,0.0
AODINT	List[float]	Aerosol optical depth range interval	0 - 2	2.0,2.0
SMRINT	List[float]	Surface meteorological range interval	0 - 2
ELEVINT*	List[float]	Scene elevation interval	2 - 2
SALTINT*	List[float]	Sensor altitude interval	2 - 2

* Required parameter

Parameter descriptions

RLUTFILI

Specifies the name of the input radiance lookup table file.

DBSRL

Specifies the input segment that contains the radiance LUT.

SPECFILO

Specifies the name of the output spectral library file.

FILOTYPE

Specifies the file format for the output spectral library file.

RSTYPE

Specifies the type of radiance spectra to be extracted.

REFLINT

Specifies, in percentage, the reflectance interval endpoints.

An endpoint value e must be such that 0 < e <= 1.

RAZINT

Specifies, in degrees, the relative view-solar azimuth (solar azimuth minus view azimuth) interval endpoints.

An endpoint value e must be such that -360 <= e <= 360.

VZAINT

Specifies, in degrees, the view zenith angle interval endpoints.

An endpoint value e must be such that 90 <= e <= 180.

SZAINT

Specifies, in degrees, the solar zenith angle interval endpoints.

An endpoint value e must be such that 0 <= e <= 90.

VWVCINT

Specifies, in g/cm^2, the atmospheric water vapor content interval endpoints.

An endpoint value e must be such that e >= 0. If the input radiance LUT was created by specifying a default atmospheric water vapor content interval, this parameter should be left unspecified.

AODINT

Specifies the aerosol optical depth interval endpoints (at 550nm).

An endpoint value e must be such that 0 <= e <= 2.

The aerosol optical depth range interval (AODINT) can be used as an alternative to the surface meteorological range interval (SMRINT) to evaluate the surface meteorological range map. Only one these two parameters can be specified.

If the input radiance LUT was created by specifying a default surface meteorological range interval, this parameter should be left unspecified.

SMRINT

Specifies, in km, the surface meteorological range interval endpoints.

An endpoint value e must be such that 0 < e.

The aerosol optical depth range interval (AODINT) can be used as an alternative to the surface meteorological range interval (SMRINT) to evaluate the surface meteorological range map. Only one these two parameters can be specified.

If the input radiance LUT was created by specifying a default surface meteorological range interval, this parameter should be left unspecified.

ELEVINT

Specifies the scene elevation interval endpoints, in meters with respect to the WGS84 vertical datum.

SALTINT

Specifies the sensor altitude interval endpoints, in meters with respect to the WGS84 vertical datum.

Details

RLUTSP is designed to be used in combination with GENRLUT and RESRLUT. It extracts radiance spectra from an input radiance lookup table (RLUT) according to user-specified table dimension intervals and outputs them to a file. Only the specified radiance spectra type is extracted. The input RLUT must conform to the RLUT format requirements and contain all mandatory metadata tags.

The function outputs only the spectra that match the specified coordinate interval criteria.

Each output spectrum will have unique name depending on its RLUT index. For example, the spectrum corresponding to multidimensional array index {0,1,2,3,4,5,6,7} will be named 0_1_2_3_4_5_6_7_LG or 0_1_2_3_4_5_6_7_LO, depending on the spectrum component chosen.

The report will list the total number of spectra extracted.

Because the RLUT binary format does not allow data inspection, RLUTSP is the only tool available for RLUT data extraction and validation.

Example

Extract all LG spectra from the RLUT stored in segment 2 of rlut.pix that satisfy the interval requirements and save them to an USGS binary library file.

from pci.rlutsp import *

rlutfili	=	"rlut.pix"	# input file
dbsrl	=	[2]	# input RLUT segment
specfilo	=	"rlutsp.spl"	# output spectra library file
filotype	=	"SPCB"	# output spectra library format
rstype	=	"LG"	# extract only at-sensor target radiance component
reflint	=	[0.05, 0.60]	# reflectance range
razint	=	[-80.8, 99.2]	# relative view-solar azimuth range
vzaint	=	[165, 180]	# view zenith angle range
szaint	=	[14.4, 14.4]	# solar zenith angle range
vwvcint	=	[]	# default VWVC range
aodint	=	[]	# default aerosol optical depth range
smrint	=	[]	# default surface meteorological range
elevint	=	[1524, 1524]	# scene elevation range
saltint	=	[21036, 21036]	# sensor altitude range

rlutsp( rlutfili, dbsrl, specfilo, filotype, rstype, reflint, razint, vzaint, szaint, vwvcint, aodint, smrint, elevint, saltint )
            

References

Staenz, K., and Williams D.J., 1997. "Retrieval of Surface Reflectance from Hyperspectral Data Using a Lookup Table Approach," Canadian Journal of Remote Sensing, Vol. 23, No. 4, pp. 354-368.