| Environments | PYTHON :: EASI :: MODELER |
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| Quick links | Description :: Parameters :: Parameter descriptions :: Details :: Algorithm :: Acknowledgements :: References :: Related |
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| Name | Type | Length | Value range |
|---|---|---|---|
| Input: Input raster channel(s)* | Raster port | 1 - 2 | |
| InputOrbit: Input satellite orbital ephemeris segment* | ORB port | 1 - 1 | |
| InputGCP: Input GCP segment | GCP port | 0 - 1 | |
| InputSAROffset: Input SAR offset segment* | Array port | 1 - 1 | |
| InputSARGain: Input SAR gain segment* | Array port | 1 - 1 | |
| Output: Output raster channel* | Raster port | 1 - 1 | |
| OutputOrbit: Output satellite orbital ephemeris segment | ORB port | 0 - 1 | |
| OutputGCP: Output GCP segment | GCP port | 0 - 1 | |
| Amplitude, Decibels, or Power | String | 0 - 1 | AMP | DB | POW Default: DB |
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Input: Input raster channel(s)
For ASAR Alternating Polarization images, only one polarization can be processed at a time.
For Single Look Complex (SLC) images, two channels must be specified.
If two channels are specified, the first channel is taken as the "I" (in-phase or real) channel and the second as the "Q" (quadrature or imaginary) channel of an SLC image. For ASAR Alternating Polarization SLC images, the two specified channels must have the same polarization.
InputOrbit: Input satellite orbital ephemeris segment
Specifies the input segment that contains the satellite orbital ephemeris data.
InputGCP: Input GCP segment
Specifies the input segment that contains the ground control points.
InputSAROffset: Input SAR offset segment
Specifies the segment that contains the input SAR offset array, including the offset value to use to convert image pixel values.
This segment is created when the satellite image is read from CD using CDASAR. It is typically labeled "SAR Offset" or "A0Scale".
InputSARGain: Input SAR gain segment
Specifies the segment that contains the input SAR gain array, consisting of a gain scaling table use to convert image pixel values.
This segment is created when the satellite image is read from CD using CDSAR or CDASAR. It is typically labeled "SAR Gain" or "AScaling".
For ASAR Alternating Polarization images, the input image will contain two SAR Gain channels, with the second layer identified as "SAR Gain, second polarization". Select the array channel that matches the polarization of the specified image layer(s) for processing.
Output: Output raster channel
Specifies the output image channel to receive the generated brightness image.
The output channel must be 32-bit real.
If the output channel is the same as the specified input channel (DBIC) of the same image file, the output image is processed correctly and overwrites the input image. This is not advised unless the input image channel is 32-bit real.
OutputOrbit: Output satellite orbital ephemeris segment
Specifies the output segment to receive the satellite orbital ephemeris data.
OutputGCP: Output GCP segment
Specifies the output segment to receive the ground control points.
Amplitude, Decibels, or Power
Specifies whether to output amplitude, power or decibel (dB) values.
DB: output decibel (dB) values.
Decibels will produce a range of real numbers that may include negative and positive values. If quantitative measurements of radar brightness over point and distributed targets is the objective, AMPORDB should be set to "DB". Because decibel values are on a logarithmic scale, some mathematical operations applied to the dB output channel may not be valid. For example, the averaging of pixels will not yield a correct mathematical result. Any such operations should be performed on either amplitude or power values and the result then converted to dB.
AMP: output amplitude values
Amplitude values (where amplitude equals the square root of the radar brightness or power) have a positive range of real values. If the imagery is to be further processed with filtering or classification, AMPORDB should be set to "AMP".
POW: output power values
Power values (where power equals the radar brightness) would have a positive range of real values.
Data may be converted from decibels to amplitude or power values (or from amplitude or power values to decibels) using the modeling functions or the MODEL function. For more information, see the Algorithm section.
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SARBETA generates a calibrated radar brightness image from the input scaled radar image (RADARSAR or ENVISAT ASAR) using the SAR offset and scaling.
The input contains the scaled radar image and the offset and gain information stored in array segments (SAR Offset, SAR Gain) to use as input.
For ASAR Alternating Polarization images only one polarization can be processed at a time.
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If the output is in decibels (when AMPORDB="DB" or AMPORDB=):
Bij = 10.0 * log10( (DN*DN + A0)/Aj )
If the output is in amplitude values (when AMPORDB="AMP"):
Bij = sqrt( (DN*DN + A0)/Aj )
If the output is in power values (when AMPORDB="POW");
Bij = ( (DN*DN) +A0)/Aj )
If there are two input channels, the first is taken as the I (in-phase or real) channel and the second as the Q (quadrature or imaginary) channel for a complex number.
If the output is in decibels (when AMPORDB="DB" or AMPORDB=):
Bij = 10.0 * log10( (DNI*DNI + DNQ*DNQ)/(Aj*Aj) )
If the output is in amplitude values (when AMPORDB="AMP"):
Bij = sqrt( (DNI*DNI + DNQ*DNQ)/(Aj*Aj) )
If the output is in power values (when AMPORDB="POW"):
Bij = ( (DNI*DNI +DNQ*DNQ)/(Aj*Aj) )
For information on the calculations shown above, refer to the papers cited in the References section.
Decibels can be converted to amplitude values using the following model:
model
%1 = (exp10( %2 / 10.0 ))^0.5
endmodel
Amplitude values can be converted to decibels using the following model:
model
%2 = 10.0 * log10( (%1)^2 )
endmodel
Amplitude values can be converted to power values using the following model:
model
%2 = %1^2
endmodel
Power values can be converted to amplitude values using the following model:
model
%2 = %1^0.5
endmodel
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PCI Geomatics received financial support for the enhancement of this software through the Earth Observation Applications Development Program (EOADP) of the Canadian Space Agency/L'Agence Spatiale Canadienne, under contract No. 9F028-2-4917/14.
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N.W.Shepherd and Associates, (February 26, 1996). 4.2 Calibration Equation for Detected Products. In Technical Note No. 4.2 CDPF Output Data Calibration (p. 9).
N.W.Shepherd and Associates, (February 26, 1996). 4.3 Calibration Equation for SLC Products. In Technical Note No. 4.2 CDPF Output Data Calibration (p. 9).
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