ANSI-C programs: par_ASAR.c
NAME
par_ASAR - reads ENVISAT ASAR data products (Wide Swath image
modes including SLC, Image Modes PRI and SLC, Alternating
Polarization modes, and Global modes) as provided by ESA and
creates the ISP image parameter and data files in the format used
by GAMMA software.
SYNOPSIS
par_ASAR <ASAR_file>
<output_name> [K_dB]
| <ASAR_file> | (input) ASAR data file including header and image as provided by ESA |
| <output_name> | (output)common part of output file names (e.g. orbit number) |
| [K_dB] | Calibration factor in dB (nominal value for all ASAR modes = 55.0), in the case a calibration factor is provided PRI images are converted to radiometrically calibrated ground-range intensity images in float format |
EXAMPLES
par_ASAR
ASA_IMM_1PXPDE20020730_095830_000001002008_00108_02166_0066.N1 20020730
Reads the ASAR IMM Mode input data file and generates:
20020730.VV.PRI.par - SLC parameter file of PRI (ground range)
image
20020730.VV.PRI - image file (short) of PRI (ground range)
image
20020730.hdr - header file (containing header only, without image
data)
par_ASAR ASA_IMM_1PXPDE20020730_095830_000001002008_00108_02166_0066.N1 02166 55.
Reads the ASAR IMM Mode input data file and generates:
20020730.VV.GRD.par - SLC parameter file of calibrated ground
range image
20020730.VV.GRD - image file (float) of calibrated ground range
image
20020730.hdr - header file (containing header only, without image
data)
DESCRIPTION
par_ASAR is the interface
between ENVISAT ASAR data in the format provided by ESA and the
format used by GAMMA software. ASAR data are procided in a single
data file. This file contains both meta data and the image data.
par_ASAR reads this input ASAR data file, extracts the parameters
required by the GAMMA software and writes out the related SLC
parameter file as well as the image file(s) in GAMMA software
format.
In addition the unchanged header part of the input file is copied to an loutput header file. This is done for later reference to the full meta data provided in the original data file. When providing only a header file as input data file (without image data) par_ASAR generates the SLC parameter file(s) without the image files. For alternating polarization modes two output SLC parameter files and two output image data files are generated.
ASAR can be operated in many different modes. In order to
facilitate the use of ASAR data par_ASAR automatically determines
the image mode of the provided data. According to the mode, the
names for the output image parameter and data files are defined.
The program supports ASAR:
- ASAR images mode (IMS, IMP, IMM, IM)
- alernating polarization mode (APS, APP, APM,
AP)
- wide swath mode (WSM, WS)
- global monitoring mode (GM1,GM)
This includes the following data types:
- SLC (IMS, APS) (slant range geometry,
scomplex)
- PRI (IMP, IMM, APP, APM, WSM, GM1) (ground
range geometry, short)
- PRI (IM, AP, WS, GM) (ground range geometry,
uchar)
The ASAR modes supported by par_ASAR and the related naming conventions are indicated in the table below:
| ASAR mode | SLC_par | image | type | format | geometry |
| IMS | *.VV.SLC.par | *.VV.SLC | SLC | SCOMPLEX | SLANT_RANGE |
| IMP | *.VV.PRI.par | *.VV.PRI | PRI | SHORT | GROUND_RANGE |
| IMM | *.VV.PRI.par | *.VV.PRI | PRI | SHORT | GROUND_RANGE |
| IM | *.VV.PRI.par | *.VV.PRI | PRI | UBYTE | GROUND_RANGE |
| APS | *.VV.SLC.par *.HH.SLC.par |
*.VV.SLC *.HH.SLC |
SLC | SCOMPLEX | SLANT_RANGE |
| APP | *.VV.PRI.par *.HH.PRI.par |
*.VV.PRI *.HH.PRI |
PRI | SHORT | GROUND_RANGE |
| APM | *.VV.PRI.par *.HH.PRI.par |
*.VV.PRI *.HH.PRI |
PRI | SHORT | GROUND_RANGE |
| AP | *.VV.PRI.par *.HH.PRI.par |
*.VV.PRI *.HH.PRI |
PRI | UBYTE | GROUND_RANGE |
| WSM | *.VV.PRI.par | *.VV.PRI | PRI | SHORT | GROUND_RANGE |
| WS | *.VV.PRI.par | *.VV.PRI | PRI | UBYTE | GROUND_RANGE |
| WSS | *.VV.IS1.SLC.par *.VV.IS2.SLC.par *.VV.IS3.SLC.par *.VV.IS4.SLC.par *.VV.IS5.SLC.par |
*.VV.IS1.SLC *.VV.IS2.SLC *.VV.IS3.SLC *.VV.IS4.SLC *.VV.IS5.SLC |
SLC Bursts | SCOMPLEX | SLANT_RANGE |
| GM1 | *.VV.PRI.par | *.VV.PRI | PRI | SHORT | GROUND_RANGE |
| GM | *.VV.PRI.par | *.VV.PRI | PRI | UBYTE | GROUND_RANGE |
ASAR swath and polarization are documented in the sensor element of the SLC parameter file. Resulting ASAR sensor types looks like ASAR_IS3_VV (image mode 3, VV polarization) or ASAR_WS_VV (wide swath VV-polarization).
For ASAR image data in ground range geometry, the ground-range to slant range polynomials are provided with the data 3 (first, center, last) and written to the SLC parameter file. This permits to re-calculation of the the slant ranges from the ground range pixel location.
When providing a calibration constant on the command line, PRI images are converted to radiometrically calibrated intensity images (instead of amplitude images) in float format (instead of short integer). According to information from ESA, 55 dB is the calibration constant for all modes. This may not be valid for early ASAR products and is also be subject to change.
For Wide-Swath Scan-SAR SLC data, multiple SLC data sets are contained withing the ASAR image product. par_ASAR generates individual SLC and SLC.par files for each of the 5 ASAR beams used in wide-swath imaging.
Geocoded ASAR products can also be converted to GAMMA software format with par_ASAR, for example in order to display the data. At present the map related geometric information is not interpreted, though.
SEE ALSO
Users Guide, GRD_to_SR, typedef_ISP.h,