PSS2C

Description

PSS2C generates two user-defined coherent channels from fully polarimetric data sets. This module can be used to synthesize any arbitrary pair of polarizations (for example, RH, VV) or compact polarimetric data sets (for example, RH, RV).

Parameters

pss2c(fili, filo, pol1, pol2)

Name	Type	Caption	Length	Value range
FILI*	str	Input polarimetric SAR image file name	1 -
FILO*	str	Output file name of synthesized coherent dual-channel SAR image	1 -
POL1*	str	First polarization to synthesize	2 -
POL2	str	Second polarization to synthesize	0 -

* Required parameter

Parameter descriptions

FILI

The name of the input polarimetric SAR data set, which must be either non-symmetrized or symmetrized fully polarimetric (quad-polarization) complex-valued data.

The input data set must already have been imported in PCIDSK (.pix) format by SARINGEST. Alternatively, it can be the key-file name of any GDB-supported POLSAR data set in its distribution format. For more information, and a complete list of supported POLSAR sensors and data products, see SARINGEST.

FILO

The name of the output file containing the two coherent channels of complex-valued, synthesized data. The output matrix type is S2c when the input data type is S3c or S4c. For all other input-matrix types, the output is written as a covariance matrix with two real channels and one complex-valued channel (matrix type C2r1c).

POL1

The transmit and receive polarizations to synthesize for the first channel (TPSI, TCHI, RPSI, and RCHI), where:

• TPSI is the transmit orientation
• TCHI is the transmit ellipticity
• RPSI is the receive orientation
• RCHI is the receive ellipticity

Standard configurations, such as linear-horizontal (H), linear-vertical (V), left-circular (L), and right-circular (R) are supported. Non-standard configurations require four floating-point values, orientation and ellipticity for transmit, and orientation and ellipticity for receive.

• "rh": case-insensitive, predefined transmit and receive
• "Rh": case-insensitive, predefined transmit and receive
• "rH": case-insensitive, predefined transmit and receive
• "0,-45,H": transmit TPSI and TCHI followed by predefined receive
• "0,-45,h": transmit TPSI and TCHI followed by predefined receive
• "R,0,0": predefined transmit followed by receive RPSI and RCHI
• "r,0,0": predefined transmit followed by receive RPSI and RCHI
• "0,-45,0,0": transmit TPSI and TCHI followed by receive RPSI and RCHI

POL2

The transmit and receive polarizations to use for the second channel. The default is the compact polarization of POL1. If only one orientation and ellipticity is provided, it is assumed to represent the receive antenna, and the transmit polarization will match that of POL1.

• (blank): the compact configuration (assuming the value of POL1 is RH) with identical transmit (R) and orthogonal receive (V)
• "V": assumed transmit is R with predefined receive
• "v": assumed transmit is R with predefined receive
• "90,0": assumed transmit is R with receive RPSI and RCHI provided
• "rv": case-insensitive, predefined transmit and receive
• "Rv": case-insensitive, predefined transmit and receive
• "rV": case-insensitive, predefined transmit and receive
• "0,-45,V": transmit TPSI and TCHI followed by predefined receive
• "0,-45,v": transmit TPSI and TCHI followed by predefined receive
• "R,90,0": predefined transmit followed by receive RPSI and RCHI
• "r,90,0": predefined transmit followed by receive RPSI and RCHI
• "0,-45,90,0": transmit TPSI and TCHI followed by receive RPSI and RCHI

This parameter is optional.

Details

PSS2C generates a pair of synthesized coherent channels based on user-defined transmit and receive polarizations.

The input file must represent a non-symmetrized or symmetrized fully polarimetric (quad-polarization) SAR data set in scattering-matrix format.

The input file must be a data set that is already imported into the PCIDSK format by SARINGEST. Alternatively, it can be the key-file name of any GDB-supported POLSAR data set in its distribution format. For more information, and a complete list of supported POLSAR sensors and data products, see SARINGEST.

For a fully polarized electromagnetic wave, the tip of the electric-field vector traces an ellipse on a plane perpendicular to the wave-propagation direction. The polarization ellipse is defined by two parameters: orientation and ellipticity. The orientation of the ellipse, PSI, is defined as the angle made by the major axis of the ellipse relative to horizontal, and can range from -90 through +90 degrees. The ellipticity angle, CHI, is defined as the arctangent of the ratio of the minor axis to major axis of the ellipse, and can range from -45 through +45 degrees. The transmit (TPSI, TCHI) and receive (RPSI, RCHI) values are recorded as metadata for each output layer.

Circular and linear polarizations are the limiting aspects of the ellipse. With circular polarizations, the orientation is 0 degrees and the ellipticity is 45 degrees. An ellipticity of CHI of +45 degrees corresponds to a left-circular polarization and -45 degrees corresponds to a right-circular polarization. With linear polarizations, the orientation of the axis is defined in degrees relative to the horizontal axis and the ellipticity is set to zero. Setting the orientation of PSI to zero corresponds to a horizontal polarization and 90 corresponds to a vertical polarization.

The synthesized output for each channel is defined by the orientation and ellipticity of the transmitter followed by the orientation and ellipticity of the receiver. A number of standard polarizations have been predefined. These include linear-horizontal (H=h=0, 0), linear-vertical (V=v=90, 0), left-circular (L=l=0, 45) and right-circular (R=r=0, -45). For non-standard polarizations, the orientation and ellipticity values for the transmitter and receiver are required.

Example

Create a synthesized data set representing a right-circular transmitter (R) with linear-horizontal (H) and a linear-vertical (V) receive antennae using RADARSAT-2 full-quad data as input.

from pci.pss2c import *

fili	=	"rsat2.pix"
filo	=	"rsat2_LR.pix"
tpsi	=	[0]
rpsi	=	[0]
tchi	=	[45]
rchi	=	-[45]
scaletyp	= []

pss2c( fili, filo, tpsi, rpsi, tchi, rchi, scaletyp )

Algorithm

PSS2C first creates the linear polarization unit vectors for transmit and receive in the horizontal-vertical basis. The vectors are constructed from the orientation and ellipticity angles of the polarizations specified in the parameters TPSI, TCHI, RPSI, and RCHI.

For each channel, the synthesized output is generated by multiplying the unit vector of the transmit polarization by the original full-quad-scattering matrix. The intermediate result is then multiplied by the transpose of the unit vector representing the receive polarization. For scattering input (S3c or S4c) the output is written as two complex-valued scattering channels (matrix type S2c). For all covariance, coherence or Kennaugh input, the output is written as a covariance matrix with two real channels representing the intensities and a complex-valued channel representing the complex covariance of the requested polarizations.