Environments | PYTHON :: EASI :: MODELER |
Batch Mode | Yes |
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Name | Type | Length | Value range |
---|---|---|---|
InputOrbit: Input satellite orbital ephemeris segment* | ORB port | 1 - 1 | |
InputSAROffset: Input SAR Offset segment* | Array port | 1 - 1 | |
OutputIncAngle: Output SAR incident angle segment | Array port | 0 - 1 |
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InputOrbit: Input satellite orbital ephemeris segment
Specifies the input segment that contains the satellite orbital ephemeris data.
The orbital segment is created when the satellite image is read from CD using CDSAR.
InputSAROffset: Input SAR Offset segment
Specifies the input array segment that contains the SAR Offset data.
The segment is created when the satellite image is read from CD using CDSAR; it is typically labeled "SAR Offset" or "A0Scale".
OutputIncAngle: Output SAR incident angle segment
Upons successful completion of SARINCD, this parameter receives the number of the new array segment of incident angles.
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SARINCD produces a table of incident angles that correspond to the table of SAR gain scaling values produced when an image is read from a CD using CDSAR. The input image file (FILE) contains the orbit segment (ORBIT) and the SAR Offset array segment (A0SEG) required as input.
SARINCD is not required for ENVISAT ASAR images. For ASAR images, the incident angle information is extracted from the ESA-format image and stored in the Incident Angle segment by the CDASAR function.
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Calculate the earth radius (r) at the image center (start of image for swath products) and the orbit altitude (h).
tan_plat_lat = ( tan(plat_lat * PI/180) )**2 sqrt(1 + tan_plat_lat) r = ellip_min * ---------------------------------------------- * 1000 sqrt(ellip_min**2/ellip_maj**2 + tan_plat_lat) h = eph_orb(1) * 1000 - r
For each image column, calculate the slant range (RSi).
For detected products stored in ground range (not SLC):
RSi = SRGR(1) + (i * dRg) * SRGR(2) + (i * dRg)**2 * SRGR(3) + (i * dRg)**3 * SRGR(4) + (i * dRg)**4 * SRGR(5) + (i * dRg)**5 * SRGR(6)
For SLC products (stored in slant range):
RSi = SRfirst + (i * dRg)
For each image column, calculate the incident angle (Ii):
Ii = acos( (h*h - RSi*RSi + 2*r*h)/(2*RSi*r) ) * 180/PI
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The calculations in the Algorithm come from:
"4.4 Conversion to Sigma Nought" and "Appendix A, Supporting calculations" of Technical Note No. 4.2 CDPF Output Data Calibration", N.W.Shepherd and Associates, February 26, 1996.
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