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Name | Type | Caption | Length | Value range |
---|---|---|---|---|
FILE* | String | Input file name | 1 - 192 | |
ORBIT* | Integer | Input satellite orbital ephemeris segment | 1 - 1 | |
A0SEG* | Integer | Input SAR Offset segment | 1 - 1 | |
INCIDSEG | Integer | Output SAR incident angle segment | 0 - 1 | |
MONITOR | String | Monitor mode | 0 - 3 | ON, OFF Default: ON |
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FILE
Specifies the name of the PCIDSK file that contains the orbit segment and SAR Gain array segment to process.
ORBIT
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.
A0SEG
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".
INCIDSEG
Upons successful completion of SARINCD, this parameter receives the number of the new array segment of incident angles.
MONITOR
The program progress can be monitored by printing the percentage of processing completed. A system parameter, MONITOR, controls this activity.
Available options are:
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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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Create an Array Segment of Incidence Angles (incidseg) using asarapp.pix.
EASI>file = 'radarbeam2.pix' ! input file EASI>orbit = 2 ! input orbit segment EASI>a0seg = 3 ! input SAR Offset segment EASI>run SARINCD
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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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