SARSUBNOISE

Description

SARSUBNOISE creates an output file with the intensities of the original layers reduced by the noise threshold level (expressed in decibels (dB)) as specified by the THRES parameter.

Parameters

sarsubnoise(fili, thres, filo)

Name	Type	Caption	Length	Value range
FILI *	str	Input polarimetric SAR image	1 -
THRES	List[float]	Noise threshold in dB.	0 - 1
FILO *	str	Output total power image	1 -

* Required parameter

Parameter descriptions

FILI

The name of the SAR input file. The input data set must have already been imported into the PCIDSK (.pix) format with SARINGEST or SARINGESTAOI. The input can also be the key-file name of any GDB-supported POLSAR data set in its vendor distribution format. For more information, including a complete list of supported SAR sensors and data products, follow the link to SARINGEST or SARINGESTAOI at the end of this topic.

THRES

This value (in decibels) represents the value to be subtracted from the intensity of each polarization. If no value is specified, a nominal sensor specific value is extracted from the "NOISE_THRESHOLD" metadata value associated with the data set.

FILO

The name of the output file that will hold the noise-subtracted intensities. The output file preserves the size (rows, columns, channels), matrix type (scattering, covariance, coherence, or Kennaugh) and representation (intensity, amplitude, decibels) of the input file. The file name you specify must not already exist.

Details

SARSUBNOISE examines the matrix type (i.e. scattering, covariance, coherence, Kennaugh) of the input file and the data representation of each channel (e.g. intensity, amplitude or decibels). Each input channel is converted to intensity (a.k.a. power). The threshold value (in dB) is subtracted from the original channel intensity. The noise threshold value may be entered by the user or extracted from the value stored in the metadata (as NOISE_THRESHOLD) if this parameter is left blank. The threshold value is applied to all channels. If the corrected intensity value is less than zero, the output value is replaced with zero. The intensity values are then converted back to their original representation (one of intensity, amplitude, or decibel) and matrix type (scattering, covariance, coherence or Kennaugh).

Examples

Reduce noise for a RADARSAT-2 SLC image that has already been imported into the PCIDSK (.pix) format by SARINGEST. An empty value for THRES will use the metadata's stored noise value.

from pci.sarsubnoise import sarsubnoise

fili	=	"rsat2_slc.pix"
THRES  =   []
filo	=	"rsat2_pow.pix"

sarsubnoise( fili, THRES, filo )
    

Reduce noise for a RADARSAT-2 SLC image that has already been imported into the PCIDSK (.pix) format by -15 decibels.

from pci.sarsubnoise import sarsubnoise

fili	=	"rsat2_slc.pix"
THRES	=	[-15]
filo	=	"rsat2_pow.pix"

sarsubnoise( fili, THRES, filo )
    

Reduce noise for a RADARSAT-2 detected (amplitude) image by converting from amplitude to intensity, removing the threshold noise level of -10 decibels, and restoring the modified values back to amplitude.

from pci.sarsubnoise import sarsubnoise

fili	=	"rsat2_amp.pix"
THRES	=	[-10]
filo	=	"rsat2_pow.pix"

sarsubnoise( fili, THRES, filo )