ANSI-C program: SLC_copy.c
NAME
SLC_copy - Copy user defined image segment from input SLC
(fcomplex or scomplex) to output SLC (fcomplex or scomplex).
SYNOPSIS
SLC_copy <SLC_in> <SLC_par_in>
<SLC_out> <SLC_par_out> [fcase] [sc] [roff] [nr]
[loff] [nl] [swap_IQ] [header_lines]
| <SLC_in> | (input) SLC (FCOMPLEX or SCOMPLEX format) |
| <SLC_par_in> | (input) ISP SLC parameter file of input SLC |
| <SLC_out> | (output) selected SLC section (FCOMPLEX or SCOMPLEX format) |
| <SLC_par_out> | (output) ISP SLC parameter file of output SLC |
| [fcase] | data format conversion (enter - for default: output
format = input format) 1: FCOMPLEX --> FCOMPLEX (default sc = 1.0) 2: FCOMPLEX --> SCOMPLEX (default sc = 10000.0) 3: SCOMPLEX --> FCOMPLEX (default sc = 0.0001) 4: SCOMPLEX --> SCOMPLEX (default sc = 1.0) |
| [sc] | scale factor for input SLC data (enter - for default) |
| [roff] | offset to starting range sample (enter - for default: 0) |
| [nr] | number of range pixels to copy (enter - for default=0, to end of line) |
| [loff] | offset to starting line (enter - for default: 0) |
| [nl] | number of lines to copy (enter - for default = 0, to end of line) |
| [swap_IQ] | swap data (enter - for default) 0: normal (default) 1: swap real/imaginary part of complex data 2: swap left/right (near/far range) |
| [header_lines] | number of input file header lines (enter - for default:
0) NOTE: CEOS format SLC data have 1 header line |
EXAMPLES
To extract 1000 lines of 1024 range pixels skipping 216 range samples and 311 lines:
SLC_copy 19990421.slc 19990421.slc.par 19990421_section.slc 19990421_section.slc.par 1 1.0 216 1024 311 1000 (input and output SLC in fcomplex format)
SLC_copy 19990421.slc 19990421.slc.par 19990421_section_esa.slc 19990421_section_esa.slc.par 4 1.0 216 1024 311 1000 (input and output SLC in scomplex format)
SLC_copy 19990421.slc 19990421.slc.par 19990421_section.slc 19990421_section.slc.par 3 0.0001 216 1024 311 1000 (input SLC in scomplex format, output SLC in fcomplex format)
DESCRIPTION
SLC_copy extracts the user defined section
from the input SLC and writes it out as a new SLC image file.
The format of the input and output SLC can be individually selected to be either fcomplex or scomplex. Data processed with the In scomplex format each complex number consists of a pair of (2-byte) short integer (4-bytes per samples). SLC data processed by ESA PAFs is in given in scomplex format. MSP SLC images can be either fcomplex or scomplex format depending on the user inputs The following fcase values have to be selected for the 4 possible input/output format combinations:
| fcase | Input Format | Output Format | Default Scale Factor |
| 1 | fcomplex | fcomplex | 1.0 |
| 2 | fcomplex | scomplex | 10000.0 |
| 3 | scomplex | fcomplex | 0.0001 |
| 4 | scomplex | scomplex | 1.0 |
A new SLC parameter file is created to describe the geometry of the new image file. Starting, center, and ending times, and the near, center and far slant ranges are calculated for the selected SLC segment. The output SLC together with its parameter file contains the full information needed for further processing. The Doppler polynomial is adjusted for the relative offset between the image segment and the original image.
The pixel value can be scaled with a user-defined scale factor. This is necessary when changing the SLC format. Notice that the output real and imaginary parts need to be in the short integer value range if scomplex is selected as output format. On the other hand when converting data from scomplex to fcomplex format a small factor is recommended to avoid too large values that may cause overflow in later calculations.
Notice that both the real and imaginary part of the SLC values are multiplied with the scale factor. For the first range pixel and first azimuth line of the input SLC to coincide with the output image select roff=0 and loff=0, respectively. The IQ_flag allows to reverse the order of real and imaginary part of the SLC. This option was added some ESA_PAFs distributed SLC data with the IQ values reversed.
Notice: CEOS format SLCs have 1 CEOS file header
line. SLC data produced by the MSP are without header
lines.
OPTIONS
The selected image section may extend outside of the range of
valid data of the input SLC. The NULL value assigned to these
values is (0.0,0.0) in fcomplex and (0,0) in scomplex format.
SLC_copy may also be used to compress MSP processed SLC data to
scomplex format with a reduction of the data volume by a factor
of 2.
SEE ALSO
SLC_par, DISP program cp_data.